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Commit f08c9ff8 authored by Peter Eisentraut's avatar Peter Eisentraut
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Make the CREATE TABLE ref page more readable and update some information.

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doc/src/sgml/ref/alter_table.sgml
View file @ f08c9ff8
<!-- <!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.29 2001/10/12 00:07:14 tgl Exp $ $Header: /cvsroot/pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.30 2001/10/22 18:14:47 petere Exp $
Postgres documentation Postgres documentation
--> -->
...@@ -161,15 +161,14 @@ ALTER TABLE <replaceable class="PARAMETER">table</replaceable> ...@@ -161,15 +161,14 @@ ALTER TABLE <replaceable class="PARAMETER">table</replaceable>
<para> <para>
<command>ALTER TABLE</command> changes the definition of an existing table. <command>ALTER TABLE</command> changes the definition of an existing table.
The <literal>ADD COLUMN</literal> form adds a new column to the table The <literal>ADD COLUMN</literal> form adds a new column to the table
using the same syntax as <xref linkend="SQL-CREATETABLE" using the same syntax as <xref linkend="SQL-CREATETABLE">.
endterm="SQL-CREATETABLE-title">.
The <literal>ALTER COLUMN SET/DROP DEFAULT</literal> forms The <literal>ALTER COLUMN SET/DROP DEFAULT</literal> forms
allow you to set or remove the default for the column. Note that defaults allow you to set or remove the default for the column. Note that defaults
only apply to subsequent <command>INSERT</command> commands; they do not only apply to subsequent <command>INSERT</command> commands; they do not
cause rows already in the table to change. cause rows already in the table to change.
The <literal>ALTER COLUMN SET STATISTICS</literal> form allows you to The <literal>ALTER COLUMN SET STATISTICS</literal> form allows you to
set the statistics-gathering target for subsequent set the statistics-gathering target for subsequent
<xref linkend="sql-analyze" endterm="sql-analyze-title"> operations. <xref linkend="sql-analyze"> operations.
The <literal>RENAME</literal> clause causes the name of a table or column The <literal>RENAME</literal> clause causes the name of a table or column
to change without changing any of the data contained in to change without changing any of the data contained in
the affected table. Thus, the table or column will the affected table. Thus, the table or column will
...@@ -177,7 +176,7 @@ ALTER TABLE <replaceable class="PARAMETER">table</replaceable> ...@@ -177,7 +176,7 @@ ALTER TABLE <replaceable class="PARAMETER">table</replaceable>
executed. executed.
The ADD <replaceable class="PARAMETER">table constraint definition</replaceable> clause The ADD <replaceable class="PARAMETER">table constraint definition</replaceable> clause
adds a new constraint to the table using the same syntax as <xref adds a new constraint to the table using the same syntax as <xref
linkend="SQL-CREATETABLE" endterm="SQL-CREATETABLE-title">. linkend="SQL-CREATETABLE">.
The DROP CONSTRAINT <replaceable class="PARAMETER">constraint</replaceable> clause The DROP CONSTRAINT <replaceable class="PARAMETER">constraint</replaceable> clause
drops all CHECK constraints on the table (and its children) that match <replaceable class="PARAMETER">constraint</replaceable>. drops all CHECK constraints on the table (and its children) that match <replaceable class="PARAMETER">constraint</replaceable>.
The OWNER clause changes the owner of the table to the user <replaceable class="PARAMETER"> The OWNER clause changes the owner of the table to the user <replaceable class="PARAMETER">
...@@ -205,18 +204,17 @@ ALTER TABLE <replaceable class="PARAMETER">table</replaceable> ...@@ -205,18 +204,17 @@ ALTER TABLE <replaceable class="PARAMETER">table</replaceable>
You can use the <literal>SET DEFAULT</literal> form You can use the <literal>SET DEFAULT</literal> form
of <command>ALTER TABLE</command> to set the default later. of <command>ALTER TABLE</command> to set the default later.
(You may also want to update the already existing rows to the (You may also want to update the already existing rows to the
new default value, using <xref linkend="sql-update" new default value, using <xref linkend="sql-update">.)
endterm="sql-update-title">.)
</para> </para>
<para> <para>
Currently only CHECK constraints can be dropped from a table. The RESTRICT Currently only CHECK constraints can be dropped from a table. The RESTRICT
keyword is required, although dependencies are not checked. The CASCADE keyword is required, although dependencies are not checked. The CASCADE
option is unsupported. To remove a PRIMARY or UNIQUE constraint, drop the option is unsupported. To remove a PRIMARY or UNIQUE constraint, drop the
relevant index using the <xref linkend="SQL-DROPINDEX" endterm="SQL-DROPINDEX-TITLE"> command. relevant index using the <xref linkend="SQL-DROPINDEX"> command.
To remove FOREIGN KEY constraints you need to recreate To remove FOREIGN KEY constraints you need to recreate
and reload the table, using other parameters to the and reload the table, using other parameters to the
<xref linkend="SQL-CREATETABLE" endterm="SQL-CREATETABLE-title"> <xref linkend="SQL-CREATETABLE">
command. command.
</para> </para>
<para> <para>
......
doc/src/sgml/ref/create_table.sgml
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<!-- <!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_table.sgml,v 1.47 2001/10/09 18:46:00 petere Exp $ $Header: /cvsroot/pgsql/doc/src/sgml/ref/create_table.sgml,v 1.48 2001/10/22 18:14:47 petere Exp $
Postgres documentation Postgres documentation
--> -->
<refentry id="SQL-CREATETABLE"> <refentry id="SQL-CREATETABLE">
<refmeta> <refmeta>
<refentrytitle id="sql-createtable-title"> <refentrytitle>CREATE TABLE</refentrytitle>
CREATE TABLE
</refentrytitle>
<refmiscinfo>SQL - Language Statements</refmiscinfo> <refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta> </refmeta>
<refnamediv> <refnamediv>
<refname> <refname>CREATE TABLE</refname>
CREATE TABLE <refpurpose>define a new table</refpurpose>
</refname>
<refpurpose>
define a new table
</refpurpose>
</refnamediv> </refnamediv>
<refsynopsisdiv> <refsynopsisdiv>
<refsynopsisdivinfo> <synopsis>
<date>2001-01-11</date> CREATE [ [ LOCAL ] { TEMPORARY | TEMP } ] TABLE <replaceable class="PARAMETER">table_name</replaceable> (
</refsynopsisdivinfo> { <replaceable class="PARAMETER">column_name</replaceable> <replaceable class="PARAMETER">data_type</replaceable> [ DEFAULT <replaceable>default_expr</> ] [ <replaceable class="PARAMETER">column_constraint</replaceable> [, ... ] ]
<synopsis> | <replaceable>table_constraint</replaceable> } [, ... ]
CREATE [ TEMPORARY | TEMP ] TABLE <replaceable class="PARAMETER">table_name</replaceable> ( )
{ <replaceable class="PARAMETER">column_name</replaceable> <replaceable class="PARAMETER">type</replaceable> [ <replaceable class="PARAMETER">column_constraint</replaceable> [ ... ] ] [ INHERITS ( <replaceable>parent_table</replaceable> [, ... ] ) ]
| <replaceable>table_constraint</replaceable> } [, ... ] ) [ WITH OIDS | WITHOUT OIDS ]
[ INHERITS ( <replaceable>parent_table</replaceable> [, ... ] ) ]
[ WITH OIDS | WITHOUT OIDS ] where <replaceable class="PARAMETER">column_constraint</replaceable> is:
where <replaceable class="PARAMETER">column_constraint</replaceable> can be:
[ CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable> ] [ CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable> ]
{ NOT NULL | NULL | UNIQUE | PRIMARY KEY | DEFAULT <replaceable class="PARAMETER">value</replaceable> | CHECK (<replaceable class="PARAMETER">condition</replaceable>) | { NOT NULL | NULL | UNIQUE | PRIMARY KEY |
REFERENCES <replaceable class="PARAMETER">table</replaceable> [ ( <replaceable class="PARAMETER">column</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL ] CHECK (<replaceable class="PARAMETER">expression</replaceable>) |
[ ON DELETE <replaceable class="parameter">action</replaceable> ] [ ON UPDATE <replaceable class="parameter">action</replaceable> ] REFERENCES <replaceable class="PARAMETER">reftable</replaceable> [ ( <replaceable class="PARAMETER">refcolumn</replaceable> ) ] [ MATCH FULL | MATCH PARTIAL ]
[ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ] [ ON DELETE <replaceable class="parameter">action</replaceable> ] [ ON UPDATE <replaceable class="parameter">action</replaceable> ] }
} [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
and <replaceable class="PARAMETER">table_constraint</replaceable> is:
and <replaceable class="PARAMETER">table_constraint</replaceable> can be:
[ CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable> ] [ CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable> ]
{ UNIQUE ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] ) | { UNIQUE ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] ) |
PRIMARY KEY ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] ) | PRIMARY KEY ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] ) |
CHECK ( <replaceable class="PARAMETER">condition</replaceable> ) | CHECK ( <replaceable class="PARAMETER">expression</replaceable> ) |
FOREIGN KEY ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] ) REFERENCES <replaceable class="PARAMETER">table</replaceable> [ ( <replaceable class="PARAMETER">column</replaceable> [, ... ] ) ] FOREIGN KEY ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] ) REFERENCES <replaceable class="PARAMETER">reftable</replaceable> [ ( <replaceable class="PARAMETER">refcolumn</replaceable> [, ... ] ) ]
[ MATCH FULL | MATCH PARTIAL ] [ ON DELETE <replaceable class="parameter">action</replaceable> ] [ ON UPDATE <replaceable class="parameter">action</replaceable> ] [ MATCH FULL | MATCH PARTIAL ] [ ON DELETE <replaceable class="parameter">action</replaceable> ] [ ON UPDATE <replaceable class="parameter">action</replaceable> ] }
[ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ] [ DEFERRABLE | NOT DEFERRABLE ] [ INITIALLY DEFERRED | INITIALLY IMMEDIATE ]
} </synopsis>
</synopsis>
</refsynopsisdiv>
<refsect1 id="SQL-CREATETABLE-description">
<title>Description</title>
<para>
<command>CREATE TABLE</command> will create a new, initially empty table
in the current database. The table will be owned by the user issuing the
command.
</para>
<refsect2 id="R2-SQL-CREATETABLE-1"> <para>
<title> <command>CREATE TABLE</command> also automatically creates a data
Inputs type that represents the tuple type (structure type) corresponding
</title> to one row of the table. Therefore, tables cannot have the same
name as any existing data type.
</para>
<para>
A table cannot have more than 1600 columns. (In practice, the
effective limit is lower because of tuple-length constraints). A
table cannot have the same name as a system catalog table.
</para>
<para>
The optional constraint clauses specify constraints (or tests) that
new or updated rows must satisfy for an insert or update operation
to succeed. A constraint is a named rule: an SQL object which
helps define valid sets of values by putting limits on the results
of insert, update, or delete operations performed on a table.
</para>
<para> <para>
There are two ways to define constraints: table constraints and
column constraints. A column constraint is defined as part of a
column definition. A table constraint definition is not tied to a
particular column, and it can encompass more than one column.
Every column constraint can also be written as a table constraint;
a column constraint is only a notational convenience if the
constraint only affects one column.
</para>
</refsect1>
<refsect1>
<title>Parameters</title>
<variablelist> <variablelist>
<varlistentry> <varlistentry>
<term>TEMPORARY or TEMP</term> <term><literal>[LOCAL] TEMPORARY</> or <literal>[LOCAL] TEMP</></term>
<listitem> <listitem>
<para> <para>
If specified, the table is created only for this session, and is If specified, the table is created as a temporary table.
automatically dropped on session exit. Temporary tables are automatically dropped at the end of a
Existing permanent tables with the same name are not visible session. Existing persistent tables with the same name are not
(in this session) while the temporary table exists. visible to the current session while the temporary table exists.
Any indexes created on a temporary table are automatically Any indexes created on a temporary table are automatically
temporary as well. temporary as well.
</para> </para>
<para>
The <literal>LOCAL</literal> word is optional. But see under
<xref linkend="sql-createtable-compatibility"
endterm="sql-createtable-compatibility-title">.
</para>
</listitem> </listitem>
</varlistentry> </varlistentry>
...@@ -74,7 +115,7 @@ and <replaceable class="PARAMETER">table_constraint</replaceable> can be: ...@@ -74,7 +115,7 @@ and <replaceable class="PARAMETER">table_constraint</replaceable> can be:
<term><replaceable class="PARAMETER">table_name</replaceable></term> <term><replaceable class="PARAMETER">table_name</replaceable></term>
<listitem> <listitem>
<para> <para>
The name of the new table to be created. The name of the table to be created.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
...@@ -89,1888 +130,693 @@ and <replaceable class="PARAMETER">table_constraint</replaceable> can be: ...@@ -89,1888 +130,693 @@ and <replaceable class="PARAMETER">table_constraint</replaceable> can be:
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
<term><replaceable class="PARAMETER">type</replaceable></term> <term><replaceable class="PARAMETER">data_type</replaceable></term>
<listitem> <listitem>
<para> <para>
The type of the column. This may include array specifiers. The data type of the column. This may include array specifiers.
Refer to the <citetitle>PostgreSQL User's Guide</citetitle> for Refer to the <citetitle>User's Guide</citetitle> for further
further information about data types and arrays. information about data types and arrays.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
<term><replaceable class="PARAMETER">parent_table</replaceable></term> <term><literal>DEFAULT
<replaceable>default_expr</replaceable></literal></term>
<listitem> <listitem>
<para> <para>
The optional INHERITS clause specifies a list of table The <literal>DEFAULT</> clause assigns a default data value for
names from which this table automatically inherits all fields. the column whose column definition it appears within. The value
is any variable-free expression (subselects and cross-references
to other columns in the current table are not allowed). The
data type of the default expression must match the data type of the
column.
</para> </para>
</listitem>
</varlistentry>
<varlistentry>
<term>WITH OIDS or WITHOUT OIDS</term>
<listitem>
<para> <para>
This optional clause specifies whether rows of the new table should The default expression will be used in any insert operation that
have OIDs (object identifiers) assigned to them. The default is does not specify a value for the column. If there is no default
WITH OIDS. (If the new table inherits from any tables that have OIDs, for a column, then the default is NULL.
then WITH OIDS is forced even if the command says WITHOUT OIDS.)
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
<term><replaceable class="PARAMETER">constraint_name</replaceable></term> <term><literal>INHERITS ( <replaceable>parent_table</replaceable> [, ... ] )</literal></term>
<listitem> <listitem>
<para> <para>
An optional name for a column or table constraint. If not specified, The optional <literal>INHERITS</> clause specifies a list of
the system generates a name. tables from which the new table automatically inherits all
columns. If the same column name exists in more than one parent
table, an error is reported unless the data types of the columns
match in each of the parent tables. If there is no conflict,
then the duplicate columns are merged to form a single column in
the new table. If the column name list of the new table
contains a column that is also inherited, the data type must
likewise match the inherited column(s), and the column
definitions are merged into one. However, inherited and new
column declarations of the same name need not specify identical
constraints: all constraints provided from any declaration are
merged together and all are applied to the new table. If the
new table explicitly specifies a default value for the column,
this default overrides any defaults from inherited declarations
of the column. Otherwise, any parents that specify default
values for the column must all specify the same default, or an
error will be reported.
</para> </para>
</listitem> <!--
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">value</replaceable></term>
<listitem>
<para> <para>
A default value for a column. Postgres automatically allows the created table to inherit
See the DEFAULT clause for more information. functions on tables above it in the inheritance hierarchy; that
is, if we create table <literal>foo</literal> inheriting from
<literal>bar</literal>, then functions that accept the tuple
type <literal>bar</literal> can also be applied to instances of
<literal>foo</literal>. (Currently, this works reliably for
functions on the first or only parent table, but not so well for
functions on additional parents.)
</para> </para>
-->
</listitem> </listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
<term><replaceable class="PARAMETER">condition</replaceable></term> <term><literal>WITH OIDS</> or <literal>WITHOUT OIDS</></term>
<listitem> <listitem>
<para> <para>
CHECK clauses specify integrity constraints or tests which new or This optional clause specifies whether rows of the new table
updated rows must satisfy for an insert or update operation to should have OIDs (object identifiers) assigned to them. The
succeed. Each constraint must be an expression producing default is to have OIDs. (If the new table inherits from any
a boolean result. tables that have OIDs, then <literal>WITH OIDS</> is forced even
A condition appearing within a column definition should reference if the command says <literal>WITHOUT OIDS</>.)
that column's value only, while a condition appearing as a table
constraint may reference multiple columns.
</para> </para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">table</replaceable></term>
<listitem>
<para> <para>
The name of an existing table to be referenced by a foreign Specifying <literal>WITHOUT OIDS</> allows the user to suppress
key constraint. generation of OIDs for rows of a table. This may be worthwhile
for large tables, since it will reduce OID consumption and
thereby postpone wraparound of the 32-bit OID counter. Once the
counter wraps around, uniqueness of OIDs can no longer be
assumed, which considerably reduces their usefulness.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
<term><replaceable class="PARAMETER">column</replaceable></term> <term><literal>CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable></literal></term>
<listitem> <listitem>
<para> <para>
The name of a column in an existing table to be referenced by a An optional name for a column or table constraint. If not specified,
foreign key constraint. If not specified, the primary key of the system generates a name.
the existing table is assumed.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
<term><replaceable class="PARAMETER">action</replaceable></term> <term><literal>NOT NULL</></term>
<listitem> <listitem>
<para> <para>
A keyword indicating the action to take when a foreign key The column is not allowed to contain NULL values. This is
constraint is violated. equivalent to the column constraint <literal>CHECK (<replaceable
class="PARAMETER">column</replaceable> NOT NULL)</literal>.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
</variablelist>
</para>
</refsect2>
<refsect2 id="R2-SQL-CREATETABLE-2">
<title>
Outputs
</title>
<para>
<variablelist>
<varlistentry> <varlistentry>
<term><computeroutput> <term><literal>NULL</></term>
CREATE
</computeroutput></term>
<listitem> <listitem>
<para> <para>
Message returned if table is successfully created. The column is allowed to contain NULL values. This is the default.
</para> </para>
</listitem>
</varlistentry>
<varlistentry>
<term><computeroutput>
ERROR
</computeroutput></term>
<listitem>
<para> <para>
Message returned if table creation failed. This clause is only available for compatibility with
This is usually accompanied by some descriptive text, such as: non-standard SQL databases. Its use is discouraged in new
<computeroutput> applications.
ERROR: Relation '<replaceable class="parameter">table</replaceable>' already exists
</computeroutput>
, which occurs at runtime if the table specified already exists
in the database.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
</variablelist>
</para>
</refsect2>
</refsynopsisdiv>
<refsect1 id="R1-SQL-CREATETABLE-1">
<title>
Description
</title>
<para>
<command>CREATE TABLE</command> will enter a new, initially empty table
into the current database. The table will be owned by the user issuing the
command.
</para>
<para>
Each <replaceable class="PARAMETER">type</replaceable>
may be a simple type, a complex type (set) or an array type.
Each attribute may be specified to be non-null and
each may have a default value, specified by the
<xref linkend="R1-SQL-DEFAULTCLAUSE-1" endterm="R1-SQL-DEFAULTCLAUSE-1-TITLE">.
</para>
<para> <varlistentry>
<note> <term><literal>UNIQUE</> (column constraint)</term>
<para> <term><literal>UNIQUE ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] )</> (table constraint)</term>
Consistent array dimensions within an
attribute are not enforced. This will likely change in a future
release.
</para>
</note>
</para>
<listitem>
<para> <para>
<command>CREATE TABLE</command> also automatically creates a data type The <literal>UNIQUE</literal> constraint specifies a rule that a
that represents the tuple type (structure type) corresponding to one group of one or more distinct columns of a table may contain
row of the table. Therefore, tables can't have the same name as any only unique values. The behavior of the unique table constraint
existing datatype. is the same as that for column constraints, with the additional
capability to span multiple columns.
</para> </para>
<para> <para>
A table can have no more than 1600 columns (in practice, the For the purpose of a unique constraint, NULL values are not
effective limit is lower because of tuple-length constraints). considered equal.
A table cannot have the same name as a system catalog table.
</para> </para>
</refsect1>
<refsect1 id="R1-SQL-INHERITSCLAUSE-1">
<title id="R1-SQL-INHERITSCLAUSE-1-TITLE">
INHERITS Clause
</title>
<para> <para>
<synopsis> Each unique table constraint must name a set of columns that is
INHERITS ( <replaceable class="PARAMETER">parent_table</replaceable> [, ... ] ) different from the set of columns named by any other unique or
</synopsis> primary key constraint defined for the table. (Otherwise it
would just be the same constraint listed twice.)
</para> </para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>PRIMARY KEY</> (column constraint)</term>
<term><literal>PRIMARY KEY ( <replaceable class="PARAMETER">column_name</replaceable> [, ... ] )</> (table constraint)</term>
<listitem>
<para> <para>
The optional INHERITS The primary key constraint specifies that a column or columns of a table
clause specifies a list of table names from which the new table may contain only unique (non-duplicate), non-NULL values.
automatically inherits all fields. If the same field name appears in Technically, <literal>PRIMARY KEY</literal> is merely a
more than one parent table, Postgres reports an error unless the field combination of <literal>UNIQUE</> and <literal>NOT NULL</>, but
definitions match in each of the parent tables. If there is no identifying a set of columns as primary key also provides
definition conflict, then the duplicate fields are merged to form a single meta-data about the design of the schema, as a primary key
field of the new table. If the new table's own field list contains a implies that other tables
field name that is also inherited, this declaration must likewise match may rely on this set of columns as a unique identifier for rows.
the inherited field(s), and the field definitions are merged into one.
</para> </para>
<para> <para>
Inherited and new field declarations of the same name must specify exactly Only one primary key can be specified for a table, whether as a
the same data type to avoid an error. They need not specify identical column constraint or a table constraint.
constraints --- all constraints provided from any declaration are merged
together and all are applied to the new table. If the new table explicitly
specifies a default value for the field, this default overrides any
defaults from inherited declarations of the field. Otherwise, any parents
that specify default values for the field must all specify the same
default, or an error will be reported.
</para> </para>
<para> <para>
Postgres automatically allows the created table to inherit functions on The primary key constraint should name a set of columns that is
tables above it in the inheritance hierarchy; that is, if we create table different from other sets of columns named by any unique
<literal>foo</literal> inheriting from <literal>bar</literal>, then constraint defined for the same table.
functions that accept the tuple type <literal>bar</literal> can also be
applied to instances of <literal>foo</literal>. (Currently, this works
reliably for functions on the first or only parent table, but not so well
for functions on additional parents.)
</para> </para>
</refsect1> </listitem>
</varlistentry>
<refsect1 id="R1-SQL-OIDSCLAUSE-1"> <varlistentry>
<title id="R1-SQL-OIDSCLAUSE-1-TITLE"> <term><literal>CHECK (<replaceable class="PARAMETER">expression</replaceable>)</literal></term>
OIDS Clause <listitem>
</title>
<para> <para>
<synopsis> <literal>CHECK</> clauses specify integrity constraints or tests
WITH OIDS | WITHOUT OIDS which new or updated rows must satisfy for an insert or update
</synopsis> operation to succeed. Each constraint must be an expression
producing a Boolean result. A condition appearing within a
column definition should reference that column's value only,
while a condition appearing as a table constraint may reference
multiple columns.
</para> </para>
<para> <para>
This clause controls whether an OID (object ID) is generated and assigned Currently, <literal>CHECK</literal> expressions cannot contain
to each row inserted into the table. The default is WITH OIDS. subselects nor refer to variables other than columns of the
Specifying WITHOUT OIDS allows the user to suppress generation of current row.
OIDs for rows of a table. This may be worthwhile for large
tables, since it will reduce OID consumption and thereby postpone
wraparound of the 32-bit OID counter. Once the counter wraps around,
uniqueness of OIDs can no longer be assumed, which considerably reduces
their usefulness.
</para> </para>
<para> </listitem>
Whenever an application makes use of OIDs to identify specific rows of </varlistentry>
a table, it is recommended that you create a unique index on OID for
that table, to ensure that OIDs in the table will indeed uniquely
identify rows even after counter wraparound. (An index on OID is needed
anyway for fast lookup of rows by OID.) Avoid assuming that OIDs are
unique across tables --- if you need a database-wide unique identifier,
use the combination of tableoid and row OID for the purpose. (It is
likely that future Postgres releases will use a separate OID counter
for each table, so that it will be <emphasis>necessary</> not optional
to include tableoid to have a unique identifier database-wide.)
</para>
<tip>
<para>
WITHOUT OIDS is not recommended for tables with no primary key, since
without either an OID or a unique data key, it is difficult to identify
specific rows.
</para>
</tip>
</refsect1>
<refsect1 id="R1-SQL-DEFAULTCLAUSE-1"> <varlistentry>
<title id="R1-SQL-DEFAULTCLAUSE-1-TITLE"> <term><literal>REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ] [ MATCH <replaceable class="parameter">matchtype</replaceable> ] [ ON DELETE <replaceable class="parameter">action</replaceable> ] [ ON UPDATE <replaceable class="parameter">action</replaceable> ]</literal> (column constraint)</term>
DEFAULT Clause
</title>
<para>
<synopsis>
DEFAULT <replaceable class="PARAMETER">value</replaceable>
</synopsis>
</para>
<para> <term><literal>FOREIGN KEY ( <replaceable class="parameter">column</replaceable> [, ... ] )
The DEFAULT clause assigns a default data value for the column whose REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> [, ... ] ) ]
column definition it appears within. The value is any variable-free [ MATCH <replaceable class="parameter">matchtype</replaceable> ]
expression (note that sub-selects and cross-references to other [ ON DELETE <replaceable class="parameter">action</replaceable> ]
columns in the current table are not supported). [ ON UPDATE <replaceable class="parameter">action</replaceable> ]</literal>
The data type of a default value must match the column definition's (table constraint)</term>
data type.
</para>
<listitem>
<para> <para>
The DEFAULT expression will be used in any INSERT operation that does The <literal>REFERENCES</literal> column constraint specifies
not specify a value for the column. If there is no DEFAULT clause, that a group of one or more columns of the new table must only
then the default is NULL. contain values which match against values in the referenced
column(s) <replaceable class="parameter">refcolumn</replaceable>
of the referenced table <replaceable
class="parameter">reftable</replaceable>. If <replaceable
class="parameter">refcolumn</replaceable> is omitted, the
primary key of the <replaceable
class="parameter">reftable</replaceable> is used. The
referenced columns must be the columns of a unique or primary
key constraint in the referenced table.
</para> </para>
<refsect2 id="R2-SQL-DEFAULTCLAUSE-2">
<title>
Usage
</title>
<para> <para>
<programlisting> A value added to these columns is matched against the values of
CREATE TABLE distributors ( the referenced table and referenced columns using the given
name VARCHAR(40) DEFAULT 'luso films', match type. There are three match types: <literal>MATCH
did INTEGER DEFAULT NEXTVAL('distributors_serial'), FULL</>, <literal>MATCH PARTIAL</>, and a default match type if
modtime TIMESTAMP DEFAULT now() none is specified. <literal>MATCH FULL</> will not allow one
); column of a multi-column foreign key to be NULL unless all
</programlisting> foreign key columns are NULL. The default match type allows some
The above assigns a literal constant default value for the column foreign key columns to be NULL while other parts of the foreign
<literal>name</literal>, and arranges for the default value of column key are not NULL. <literal>MATCH PARTIAL</> is not yet
<literal>did</literal> to be generated by selecting the next value of a implemented.
sequence object. The default value of <literal>modtime</literal> will
be the time at which the row is inserted.
</para> </para>
<para> <para>
It is worth remarking that In addition, when the data in the referenced columns is changed,
<programlisting> certain actions are performed on the data in this table's
modtime TIMESTAMP DEFAULT 'now' columns. The <literal>ON DELETE</literal> clause specifies the
</programlisting> action to do when a referenced row in the referenced table is
would produce a result that is probably not the intended one: the being deleted. Likewise, the <literal>ON UPDATE</literal>
string <literal>'now'</literal> will be coerced to a timestamp value clause specifies the action to perform when a referenced column
immediately, and so the default value of <literal>modtime</literal> will in the referenced table is being updated to a new value. If the
always be the time of table creation. This difficulty is avoided by row is updated, but the referenced column is not actually
specifying the default value as a function call. changed, no action is done. There are the following possible
</para> actions for each clause:
</refsect2>
</refsect1>
<refsect1 id="R1-SQL-COLUMNCONSTRAINT-1"> <variablelist>
<title id="R1-SQL-COLUMNCONSTRAINT-1-TITLE"> <varlistentry>
Column Constraints <term><literal>NO ACTION</literal></term>
</title> <listitem>
<para> <para>
<synopsis> Produce an error indicating that the deletion or update
[ CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> ] { would create a foreign key constraint violation. This is
NULL | NOT NULL | UNIQUE | PRIMARY KEY | CHECK <replaceable the default action.
class="parameter">condition</replaceable> |
REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ]
[ MATCH <replaceable class="parameter">matchtype</replaceable> ]
[ ON DELETE <replaceable class="parameter">action</replaceable> ]
[ ON UPDATE <replaceable class="parameter">action</replaceable> ]
[ [ NOT ] DEFERRABLE ]
[ INITIALLY <replaceable class="parameter">checktime</replaceable> ] }
</synopsis>
</para> </para>
</listitem>
</varlistentry>
<refsect2 id="R2-SQL-COLUMNCONSTRAINT-1">
<title>
Inputs
</title>
<para>
<variablelist>
<varlistentry> <varlistentry>
<term><replaceable class="parameter">constraint_name</replaceable></term> <term><literal>RESTRICT</literal></term>
<listitem> <listitem>
<para> <para>
An arbitrary name given to a constraint clause. Same as <literal>NO ACTION</literal>.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
<term>NULL</term> <term><literal>CASCADE</literal></term>
<listitem> <listitem>
<para> <para>
The column is allowed to contain NULL values. This is the default. Delete any rows referencing the deleted row, or update the
value of the referencing column to the new value of the
referenced column, respectively.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
<term>NOT NULL</term> <term><literal>SET NULL</literal></term>
<listitem> <listitem>
<para> <para>
The column is not allowed to contain NULL values. Set the referencing column values to NULL.
This is equivalent to the column constraint
CHECK (<replaceable class="PARAMETER">column</replaceable> NOT NULL).
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
<term>UNIQUE</term> <term><literal>SET DEFAULT</literal></term>
<listitem> <listitem>
<para> <para>
The column must have unique values. In <productname>Postgres</productname> Set the referencing column values to their default value.
this is enforced by automatic creation of a unique index on the column. </para>
</listitem>
</varlistentry>
</variablelist>
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
<term>PRIMARY KEY</term> <term><literal>DEFERRABLE</literal> or <literal>NOT DEFERRABLE</literal></term>
<listitem> <listitem>
<para> <para>
This column is a primary key, which implies that other tables may rely This controls whether the constraint can be deferred. A
on this column as a unique identifier for rows. Both UNIQUE and constraint that is not deferrable will be checked immediately
NOT NULL are implied by PRIMARY KEY. See PRIMARY KEY for more after every command. Checking of constraints that are
information. deferrable may be postponed until the end of the transaction
(using the <xref linkend="sql-set-constraints"> command).
<literal>NOT DEFERRABLE</literal> is the default. Only foreign
key constraints currently accept this clause. All other
constraint types are not deferrable.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
<term> <term><literal>INITIALLY IMMEDIATE</literal> or <literal>INITIALLY DEFERRED</literal></term>
<replaceable class="parameter">condition</replaceable>
</term>
<listitem> <listitem>
<para> <para>
An arbitrary boolean-valued constraint condition. If a constraint is deferrable, this clause specifies the default
time to check the constraint. If the constraint is
<literal>INITIALLY IMMEDIATE</literal>, it is checked after each
statement. This is the default. If the constraint is
<literal>INITIALLY DEFERRED</literal>, it is checked only at the
end of the transaction. The constraint check time can be
altered with the <xref linkend="sql-set-constraints"> command.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
</variablelist> </variablelist>
</para> </refsect1>
</refsect2>
<refsect2 id="R2-SQL-COLUMNCONSTRAINT-2">
<title>
Description
</title>
<para> <refsect1 id="SQL-CREATETABLE-diagnostics">
The optional constraint clauses specify constraints or tests which <title>Diagnostics</title>
new or updated rows must satisfy for an insert or update
operation to succeed.
</para>
<para> <msgset>
A constraint is a named rule: an SQL object which helps define <msgentry>
valid sets of values by putting limits on the results of INSERT, <msg>
UPDATE or DELETE operations performed on a table. <msgmain>
</para> <msgtext>
<simpara><computeroutput>CREATE</computeroutput></simpara>
</msgtext>
</msgmain>
</msg>
<msgexplan>
<para> <para>
There are two ways to define integrity constraints: Message returned if table is successfully created.
table constraints, covered later, and column constraints, covered here.
</para> </para>
</msgexplan>
</msgentry>
<para>
A column constraint is an integrity constraint defined as part of a
column definition, and logically becomes a table constraint as soon
as it is created. The column constraints available are:
<simplelist columns="1"> <msgentry>
<member>PRIMARY KEY</member> <msg>
<member>REFERENCES</member> <msgmain>
<member>UNIQUE</member> <msgtext>
<member>CHECK</member> <simpara><computeroutput>ERROR</computeroutput></simpara>
<member>NOT NULL</member> </msgtext>
</simplelist> </msgmain>
</para> </msg>
</refsect2>
<refsect2 id="R2-SQL-NOTNULL-1"> <msgexplan>
<title>
NOT NULL Constraint
</title>
<synopsis>
[ CONSTRAINT <replaceable class="parameter">name</replaceable> ] NOT NULL
</synopsis>
<para> <para>
The NOT NULL constraint specifies a rule that a column may Message returned if table creation failed. This is usually
contain only non-null values. accompanied by some descriptive text, such as:
This is a column constraint only, and not allowed <computeroutput>ERROR: Relation '<replaceable
as a table constraint. class="parameter">table</replaceable>' already
exists</computeroutput>, which occurs at runtime if the table
specified already exists in the database.
</para> </para>
</msgexplan>
</msgentry>
</msgset>
</refsect1>
<refsect3 id="R3-SQL-NOTNULL-1">
<title> <refsect1 id="SQL-CREATETABLE-notes">
Outputs <title>Notes</title>
</title>
<para> <itemizedlist>
<variablelist>
<varlistentry>
<term><replaceable>status</replaceable></term>
<listitem>
<para>
<variablelist>
<varlistentry>
<term><computeroutput>
ERROR: ExecAppend: Fail to add null value in not null attribute "<replaceable class="parameter">column</replaceable>".
</computeroutput></term>
<listitem> <listitem>
<para> <para>
This error occurs at runtime if one tries to insert a null value Whenever an application makes use of OIDs to identify specific
into a column which has a NOT NULL constraint. rows of a table, it is recommended to create a unique constraint
</para> on the <structfield>oid</> column of that table, to ensure that
</listitem> OIDs in the table will indeed uniquely identify rows even after
</varlistentry> counter wraparound. Avoid assuming that OIDs are unique across
</variablelist> tables; if you need a database-wide unique identifier, use the
</para> combination of <structfield>tableoid</> and row OID for the
</listitem> purpose. (It is likely that future <productname>PostgreSQL</>
</varlistentry> releases will use a separate OID counter for each table, so that
</variablelist> it will be <emphasis>necessary</>, not optional, to include
<structfield>tableoid</> to have a unique identifier
database-wide.)
</para> </para>
</refsect3>
<refsect3 id="R3-SQL-NOTNULL-2"> <tip>
<title>
Description
</title>
<para> <para>
The use of <literal>WITHOUT OIDS</literal> is not recommended
for tables with no primary key, since without either an OID or a
unique data key, it is difficult to identify specific rows.
</para> </para>
</refsect3> </tip>
</listitem>
<refsect3 id="R3-SQL-NOTNULL-3">
<title>
Usage
</title>
<listitem>
<para> <para>
Define two NOT NULL column constraints on the table <productname>PostgreSQL</productname> automatically creates an
<classname>distributors</classname>, index for each unique constraint and primary key constraint to
one of which is explicitly given a name: enforce the uniqueness. Thus, it is not necessary to create an
explicit index for primary key columns. (See <xref
<programlisting> linkend="sql-createindex"> for more information.)
CREATE TABLE distributors (
did DECIMAL(3) CONSTRAINT no_null NOT NULL,
name VARCHAR(40) NOT NULL
);
</programlisting>
</para> </para>
</refsect3> </listitem>
</refsect2>
<refsect2 id="R2-SQL-UNIQUECLAUSE-1">
<title>
UNIQUE Constraint
</title>
<synopsis>
[ CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> ] UNIQUE
</synopsis>
<refsect3>
<title>Inputs</title>
<para>
<variablelist>
<varlistentry>
<term><replaceable class="parameter">constraint_name</replaceable></term>
<listitem> <listitem>
<para> <para>
An arbitrary name given to a constraint clause. The SQL92 standard says that <literal>CHECK</> column constraints
may only refer to the column they apply to; only
<literal>CHECK</> table constraints may refer to multiple
columns. <productname>PostgreSQL</productname> does not enforce
this restriction; it treats column and table check constraints
alike.
</para> </para>
</listitem> </listitem>
</varlistentry>
</variablelist>
</para>
</refsect3>
<refsect3>
<title>Outputs</title>
<para>
<variablelist>
<varlistentry>
<term><replaceable>status</replaceable></term>
<listitem>
<para>
<variablelist>
<varlistentry>
<term><computeroutput>
ERROR: Cannot insert a duplicate key into a unique index.
</computeroutput></term>
<listitem> <listitem>
<para> <para>
This error occurs at runtime if one tries to insert a Unique constraints and primary keys are not inherited in the
duplicate value into a column. current implementation. This makes the combination of
</para> inheritance and unique constraints rather disfunctional.
</listitem>
</varlistentry>
</variablelist>
</para> </para>
</listitem> </listitem>
</varlistentry> </itemizedlist>
</variablelist> </refsect1>
</para>
</refsect3>
<refsect3>
<title> <refsect1 id="SQL-CREATETABLE-examples">
Description <title>Examples</title>
</title>
<para> <para>
The UNIQUE constraint specifies a rule that a group of one or Create table <structname>films</> and table
more distinct columns of a table may contain only unique values. <structname>distributors</>:
<programlisting>
CREATE TABLE films (
code CHARACTER(5) CONSTRAINT firstkey PRIMARY KEY,
title CHARACTER VARYING(40) NOT NULL,
did DECIMAL(3) NOT NULL,
date_prod DATE,
kind CHAR(10),
len INTERVAL HOUR TO MINUTE
);
</programlisting>
<programlisting>
CREATE TABLE distributors (
did DECIMAL(3) PRIMARY KEY DEFAULT NEXTVAL('serial'),
name VARCHAR(40) NOT NULL CHECK (name &lt;&gt; '')
);
</programlisting>
</para> </para>
<para> <para>
The column definitions of the specified columns do not have to Create a table with a 2-dimensional array:
include a NOT NULL constraint to be included in a UNIQUE
constraint. Having more than one null value in a column without a <programlisting>
NOT NULL constraint, does not violate a UNIQUE constraint. (This CREATE TABLE array (
deviates from the <acronym>SQL92</acronym> definition, but is a vector INT[][]
more sensible convention. See the section on compatibility for more );
details.) </programlisting>
</para> </para>
<para> <para>
Each UNIQUE column constraint must name a column that is Define a unique table constraint for the table films. Unique table
different from the set of columns named by any other UNIQUE or constraints can be defined on one or more columns of the table:
PRIMARY KEY constraint defined for the table.
<programlisting>
CREATE TABLE films (
code CHAR(5),
title VARCHAR(40),
did DECIMAL(3),
date_prod DATE,
kind VARCHAR(10),
len INTERVAL HOUR TO MINUTE,
CONSTRAINT production UNIQUE(date_prod)
);
</programlisting>
</para> </para>
<note>
<para> <para>
<productname>Postgres</productname> automatically creates a unique Define a check column constraint:
index for each UNIQUE constraint, to assure
data integrity. See CREATE INDEX for more information.
</para>
</note>
</refsect3>
<refsect3 id="R3-SQL-UNIQUECLAUSE-3"> <programlisting>
<title> CREATE TABLE distributors (
Usage did DECIMAL(3) CHECK (did > 100),
</title> name VARCHAR(40)
);
</programlisting>
</para>
<para> <para>
Defines a UNIQUE constraint for the <literal>name</literal> column: Define a check table constraint:
<programlisting>
<programlisting>
CREATE TABLE distributors ( CREATE TABLE distributors (
did DECIMAL(3), did DECIMAL(3),
name VARCHAR(40) UNIQUE name VARCHAR(40)
CONSTRAINT con1 CHECK (did > 100 AND name &lt;&gt; '')
); );
</programlisting> </programlisting>
</para>
which is equivalent to the following specified as a table constraint:
<programlisting>
CREATE TABLE distributors (
did DECIMAL(3),
name VARCHAR(40),
UNIQUE(name)
);
</programlisting>
</para>
</refsect3>
</refsect2>
<refsect2 id="R2-SQL-CHECK-1">
<title>
The CHECK Constraint
</title>
<synopsis>
[ CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> ] CHECK ( <replaceable>condition</replaceable> )
</synopsis>
<refsect3 id="R3-SQL-CHECK-1">
<title>Inputs</title>
<para>
<variablelist>
<varlistentry>
<term><replaceable class="parameter">constraint_name</replaceable></term>
<listitem>
<para>
An arbitrary name given to a constraint clause.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable>condition</replaceable></term>
<listitem>
<para>
Any valid conditional expression evaluating to a boolean result.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect3>
<refsect3 id="R3-SQL-CHECK-2">
<title>
Outputs
</title>
<para>
<variablelist>
<varlistentry>
<term><replaceable>status</replaceable></term>
<listitem>
<para>
<variablelist>
<varlistentry>
<term><computeroutput>
ERROR: ExecAppend: rejected due to CHECK constraint "<replaceable class="parameter">constraint_name</replaceable>".
</computeroutput></term>
<listitem>
<para>
This error occurs at runtime if one tries to insert an illegal
value into a column subject to a CHECK constraint.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect3>
<refsect3>
<title>Description</title>
<para>
The CHECK constraint specifies a generic restriction on allowed values
within a column. The CHECK constraint is also allowed as a table
constraint.
</para>
<para>
CHECK specifies a general boolean expression involving one or more
columns of a table. A new row will be rejected if the boolean
expression evaluates to FALSE when applied to the row's values.
</para>
<para>
Currently, CHECK expressions cannot contain sub-selects nor refer
to variables other than fields of the current row.
</para>
<para>
The SQL92 standard says that CHECK column constraints may only refer
to the column they apply to; only CHECK table constraints may refer
to multiple columns.
<productname>Postgres</productname> does not enforce this restriction.
It treats column and table CHECK constraints alike.
</para>
</refsect3>
</refsect2>
<refsect2 id="R2-SQL-PRIMARYKEY-1">
<title>
PRIMARY KEY Constraint
</title>
<synopsis>
[ CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable> ] PRIMARY KEY
</synopsis>
<refsect3>
<title>Inputs</title>
<para>
<variablelist>
<varlistentry>
<term><replaceable class="PARAMETER">constraint_name</replaceable></term>
<listitem>
<para>
An arbitrary name given to a constraint clause.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect3>
<refsect3>
<title>Outputs</title>
<variablelist>
<varlistentry>
<term><computeroutput>
ERROR: Cannot insert a duplicate key into a unique index.
</computeroutput></term>
<listitem>
<para>
This occurs at runtime if one tries to insert a duplicate value into
a column subject to a PRIMARY KEY constraint.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect3>
<refsect3>
<title>Description</title>
<para>
The PRIMARY KEY column constraint specifies that a column of a
table may contain only unique (non-duplicate), non-NULL values. The
definition of the specified column does not have to include an
explicit NOT NULL constraint to be included in a PRIMARY KEY
constraint.
</para>
<para>
Only one PRIMARY KEY can be specified for a table, whether as a
column constraint or a table constraint.
</para>
</refsect3>
<refsect3 id="R3-SQL-PRIMARYKEY-3">
<title>
Notes
</title>
<para>
<productname>Postgres</productname> automatically creates
a unique index to assure
data integrity (see CREATE INDEX statement).
</para>
<para>
The PRIMARY KEY constraint should name a set of columns that is
different from other sets of columns named by any UNIQUE constraint
defined for the same table, since it will result in duplication
of equivalent indexes and unproductive additional runtime overhead.
However, <productname>Postgres</productname> does not specifically
disallow this.
</para>
</refsect3>
</refsect2>
<refsect2 id="R2-SQL-REFERENCES-1">
<refsect2info>
<date>2000-02-04</date>
</refsect2info>
<title>
REFERENCES Constraint
</title>
<synopsis>
[ CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> ] REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> ) ]
[ MATCH <replaceable class="parameter">matchtype</replaceable> ]
[ ON DELETE <replaceable class="parameter">action</replaceable> ]
[ ON UPDATE <replaceable class="parameter">action</replaceable> ]
[ [ NOT ] DEFERRABLE ]
[ INITIALLY <replaceable class="parameter">checktime</replaceable> ]
</synopsis>
<para>
The REFERENCES constraint specifies a rule that a column
value is checked against the values of another column.
REFERENCES can also be specified as part of
a FOREIGN KEY table constraint.
</para>
<refsect3 id="R3-SQL-REFERENCES-1">
<title>Inputs</title>
<para>
<variablelist>
<varlistentry>
<term><replaceable class="PARAMETER">constraint_name</replaceable></term>
<listitem>
<para>
An arbitrary name given to a constraint clause.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">reftable</replaceable></term>
<listitem>
<para>
The table that contains the data to check against.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">refcolumn</replaceable></term>
<listitem>
<para>
The column in <replaceable class="parameter">reftable</replaceable>
to check the data against. If this is not specified, the PRIMARY KEY of the
<replaceable class="parameter">reftable</replaceable> is used.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>MATCH <replaceable class="parameter">matchtype</replaceable></term>
<listitem>
<para>
There are three match types: MATCH FULL, MATCH PARTIAL, and a
default match type if none is specified. MATCH FULL will not
allow one column of a multi-column foreign key to be NULL
unless all foreign key columns are NULL. The default MATCH type
allows some foreign key columns to be NULL while other parts
of the foreign key are not NULL. MATCH PARTIAL is currently not
supported.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>ON DELETE <replaceable class="parameter">action</replaceable></term>
<listitem>
<para>
The action to do when a referenced row in the referenced table is being
deleted. There are the following actions.
<variablelist>
<varlistentry>
<term>NO ACTION</term>
<listitem>
<para>
Produce error if foreign key violated. This is the default.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>RESTRICT</term>
<listitem>
<para>
Same as NO ACTION.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>CASCADE</term>
<listitem>
<para>
Delete any rows referencing the deleted row.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>SET NULL</term>
<listitem>
<para>
Set the referencing column values to NULL.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>SET DEFAULT</term>
<listitem>
<para>
Set the referencing column values to their default value.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>ON UPDATE <replaceable class="parameter">action</replaceable></term>
<listitem>
<para>
The action to do when a referenced column in the referenced
table is being updated to a new value. If the row is updated,
but the referenced column is not changed, no action is done.
There are the following actions.
<variablelist>
<varlistentry>
<term>NO ACTION</term>
<listitem>
<para>
Produce error if foreign key violated. This is the default.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>RESTRICT</term>
<listitem>
<para>
Same as NO ACTION.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>CASCADE</term>
<listitem>
<para>
Update the value of the referencing column to the new value of the
referenced column.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>SET NULL</term>
<listitem>
<para>
Set the referencing column values to NULL.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>SET DEFAULT</term>
<listitem>
<para>
Set the referencing column values to their default value.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term> [ NOT ] DEFERRABLE </term>
<listitem>
<para>
This controls whether the constraint can be deferred to the end
of the transaction. If DEFERRABLE, SET CONSTRAINTS ALL DEFERRED
will cause the foreign key to be checked only at the end of the
transaction. NOT DEFERRABLE is the default.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>INITIALLY <replaceable class="parameter">checktime</replaceable></term>
<listitem>
<para>
<replaceable class="parameter">checktime</replaceable> has two possible values
which specify the default time to check the constraint.
<variablelist>
<varlistentry>
<term>DEFERRED</term>
<listitem>
<para>
Check constraint only at the end of the transaction.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>IMMEDIATE</term>
<listitem>
<para>
Check constraint after each statement. This is the default.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect3>
<refsect3 id="R3-SQL-REFERENCES-2">
<refsect3info>
<date>2000-02-04</date>
</refsect3info>
<title>
Outputs
</title>
<para>
<variablelist>
<varlistentry>
<term><replaceable>status</replaceable></term>
<listitem>
<para>
<variablelist>
<varlistentry>
<term><computeroutput>
ERROR: <replaceable class="parameter">name</replaceable> referential integrity violation - key referenced from
<replaceable class="parameter">table</replaceable> not found in <replaceable class="parameter">reftable</replaceable>
</computeroutput></term>
<listitem>
<para>
This error occurs at runtime if one tries to insert a value
into a column which does not have a matching column in the
referenced table.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect3>
<refsect3 id="R3-SQL-REFERENCES-3">
<title>Description</title>
<para>
The REFERENCES column constraint specifies that a
column of a table must only contain values which match against
values in a referenced column of a referenced table.
</para>
<para>
A value added to this column is matched against the values of the
referenced table and referenced column using the given match type.
In addition, when the referenced column data is changed, actions
are run upon this column's matching data.
</para>
</refsect3>
<refsect3 id="R3-SQL-REFERENCES-4">
<refsect3info>
<date>1998-09-11</date>
</refsect3info>
<title>
Notes
</title>
<para>
Currently <productname>Postgres</productname> only supports MATCH
FULL and a default match type. In addition, the referenced
columns are supposed to be the columns of a UNIQUE constraint in
the referenced table, however <productname>Postgres</productname>
does not enforce this.
</para>
</refsect3>
</refsect2>
</refsect1>
<refsect1 id="R1-SQL-TABLECONSTRAINT-1">
<title>
Table Constraints
</title>
<para>
<synopsis>
[ CONSTRAINT name ] { PRIMARY KEY | UNIQUE } ( <replaceable class="parameter">column</replaceable> [, ... ] )
[ CONSTRAINT name ] CHECK ( <replaceable>constraint</replaceable> )
[ CONSTRAINT name ] FOREIGN KEY ( <replaceable class="parameter">column</replaceable> [, ... ] )
REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> [, ... ] ) ]
[ MATCH <replaceable class="parameter">matchtype</replaceable> ]
[ ON DELETE <replaceable class="parameter">action</replaceable> ]
[ ON UPDATE <replaceable class="parameter">action</replaceable> ]
[ [ NOT ] DEFERRABLE ]
[ INITIALLY <replaceable class="parameter">checktime</replaceable> ]
</synopsis>
</para>
<refsect2 id="R2-SQL-TABLECONSTRAINT-1">
<title>
Inputs
</title>
<para>
<variablelist>
<varlistentry>
<term><replaceable class="parameter">constraint_name</replaceable></term>
<listitem>
<para>
An arbitrary name given to a constraint clause.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">column</replaceable> [, ... ]</term>
<listitem>
<para>
The column name(s) for which to define a unique index
and, for PRIMARY KEY, a NOT NULL constraint.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>CHECK ( <replaceable class="parameter">constraint</replaceable> )</term>
<listitem>
<para>
A boolean expression to be evaluated as the constraint.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect2>
<refsect2 id="R2-SQL-TABLECONSTRAINT-2">
<title>
Outputs
</title>
<para>
The possible outputs for the table constraint clause are the same
as for the corresponding portions of the column constraint clause.
</para>
</refsect2>
<refsect2 id="R2-SQL-TABLECONSTRAINT-3">
<title>
Description
</title>
<para>
A table constraint is an integrity constraint defined on one or
more columns of a table. The four variations of <quote>Table
Constraint</quote> are:
<simplelist columns="1">
<member>UNIQUE</member>
<member>CHECK</member>
<member>PRIMARY KEY</member>
<member>FOREIGN KEY</member>
</simplelist>
</para>
</refsect2>
<refsect2 id="R2-SQL-UNIQUECLAUSE-4">
<title>
UNIQUE Constraint
</title>
<para>
<synopsis>
[ CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> ] UNIQUE ( <replaceable class="parameter">column</replaceable> [, ... ] )
</synopsis>
</para>
<refsect3>
<title>Inputs</title>
<variablelist>
<varlistentry>
<term><replaceable class="parameter">constraint_name</replaceable></term>
<listitem>
<para>
An arbitrary name given to a constraint clause.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">column</replaceable></term>
<listitem>
<para>
A name of a column in a table.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect3>
<refsect3>
<title>Outputs</title>
<para>
<variablelist>
<varlistentry>
<term><replaceable>status</replaceable></term>
<listitem>
<para>
<variablelist>
<varlistentry>
<term>ERROR: Cannot insert a duplicate key into a unique index</term>
<listitem>
<para>
This error occurs at runtime if one tries to insert a
duplicate value into a column.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect3>
<refsect3>
<title>
Description
</title>
<para>
The UNIQUE constraint specifies a rule that a group of one or more
distinct columns of a table may contain only unique values. The
behavior of the UNIQUE table constraint is the same as that for
column constraints, with the additional capability to span multiple
columns.
</para>
<para>
See the section on the UNIQUE column constraint for more details.
</para>
</refsect3>
<refsect3 id="R3-SQL-UNIQUECLAUSE-4">
<title>
Usage
</title>
<para>
Prevent duplicate rows in the table distributors:
<programlisting>
CREATE TABLE distributors (
did DECIMAL(3),
name VARCHAR(40),
UNIQUE(did,name)
);
</programlisting>
</para>
</refsect3>
</refsect2>
<refsect2 id="R2-SQL-PRIMARYKEY-4">
<title>
PRIMARY KEY Constraint
</title>
<para>
<synopsis>
[ CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable> ] PRIMARY KEY ( <replaceable class="PARAMETER">column</replaceable> [, ... ] )
</synopsis>
</para>
<refsect3>
<title>Inputs</title>
<para>
<variablelist>
<varlistentry>
<term><replaceable class="PARAMETER">constraint_name</replaceable></term>
<listitem>
<para>
An arbitrary name given to a constraint clause.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">column</replaceable> [, ... ]</term>
<listitem>
<para>
The names of one or more columns in the table.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect3>
<refsect3>
<title>Outputs</title>
<variablelist>
<varlistentry>
<term><replaceable>status</replaceable></term>
<listitem>
<para>
<variablelist>
<varlistentry>
<term>ERROR: Cannot insert a duplicate key into a unique index.</term>
<listitem>
<para>
This occurs at run-time if one tries to insert a duplicate
value into a column subject to a PRIMARY KEY constraint.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect3>
<refsect3>
<title>Description</title>
<para>
The PRIMARY KEY constraint specifies a rule that a group of one
or more distinct columns of a table may contain only unique
(nonduplicate), non-null values. The column definitions of
the specified columns do not have to include a NOT NULL
constraint to be included in a PRIMARY KEY constraint.
</para>
<para>
The PRIMARY KEY table constraint is similar to that for column constraints,
with the additional capability of encompassing multiple columns.
</para>
<para>
Refer to the section on the PRIMARY KEY column constraint for more
information.
</para>
</refsect3>
</refsect2>
<refsect2 id="R2-SQL-REFERENCES-2">
<refsect2info>
<date>2000-02-04</date>
</refsect2info>
<title>
REFERENCES Constraint
</title>
<synopsis>
[ CONSTRAINT <replaceable class="parameter">constraint_name</replaceable> ] FOREIGN KEY ( <replaceable class="parameter">column</replaceable> [, ... ] )
REFERENCES <replaceable class="parameter">reftable</replaceable> [ ( <replaceable class="parameter">refcolumn</replaceable> [, ... ] ) ]
[ MATCH <replaceable class="parameter">matchtype</replaceable> ]
[ ON DELETE <replaceable class="parameter">action</replaceable> ]
[ ON UPDATE <replaceable class="parameter">action</replaceable> ]
[ [ NOT ] DEFERRABLE ]
[ INITIALLY <replaceable class="parameter">checktime</replaceable> ]
</synopsis>
<para>
The REFERENCES constraint specifies a rule that a column value or set
of column values is
checked against the values in another table.
</para>
<refsect3 id="R3-SQL-REFERENCES-5">
<title>Inputs</title>
<para>
<variablelist>
<varlistentry>
<term><replaceable class="PARAMETER">constraint_name</replaceable></term>
<listitem>
<para>
An arbitrary name given to a constraint clause.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">column</replaceable> [, ... ]</term>
<listitem>
<para>
The names of one or more columns in the table.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">reftable</replaceable></term>
<listitem>
<para>
The table that contains the data to check against.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">referenced column</replaceable> [, ... ]</term>
<listitem>
<para>
One or more columns in the <replaceable class="parameter">reftable</replaceable>
to check the data against. If this is not specified, the PRIMARY KEY of the
<replaceable class="parameter">reftable</replaceable> is used.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>MATCH <replaceable class="parameter">matchtype</replaceable></term>
<listitem>
<para>
There are three match types: MATCH FULL, MATCH PARTIAL, and a
default match type if none is specified. MATCH FULL will not
allow one column of a multi-column foreign key to be NULL
unless all foreign key columns are NULL. The default MATCH type
allows some foreign key columns to be NULL while other parts
of the foreign key are not NULL. MATCH PARTIAL is currently not
supported.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>ON DELETE <replaceable class="parameter">action</replaceable></term>
<listitem>
<para>
The action to do when a referenced row in the referenced table is being
deleted. There are the following actions.
<variablelist>
<varlistentry>
<term>NO ACTION</term>
<listitem>
<para>
Produce error if foreign key violated. This is the default.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>RESTRICT</term>
<listitem>
<para>
Same as NO ACTION.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>CASCADE</term>
<listitem>
<para>
Delete any rows referencing the deleted row.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>SET NULL</term>
<listitem>
<para>
Set the referencing column values to NULL.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>SET DEFAULT</term>
<listitem>
<para>
Set the referencing column values to their default value.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>ON UPDATE <replaceable class="parameter">action</replaceable></term>
<listitem>
<para>
The action to do when a referenced column in the referenced
table is being updated to a new value. If the row is updated,
but the referenced column is not changed, no action is done.
There are the following actions.
<variablelist>
<varlistentry>
<term>NO ACTION</term>
<listitem>
<para>
Produce error if foreign key violated. This is the default.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>RESTRICT</term>
<listitem>
<para>
Disallow update of row being referenced.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>CASCADE</term>
<listitem>
<para>
Update the value of the referencing column to the new value
of the referenced column.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>SET NULL</term>
<listitem>
<para>
Set the referencing column values to NULL.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>SET DEFAULT</term>
<listitem>
<para>
Set the referencing column values to their default value.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term> [ NOT ] DEFERRABLE </term>
<listitem>
<para>
This controls whether the constraint can be deferred to the end
of the transaction. If DEFERRABLE, SET CONSTRAINTS ALL DEFERRED
will cause the foreign key to be checked only at the end of the
transaction. NOT DEFERRABLE is the default.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>INITIALLY <replaceable class="parameter">checktime</replaceable></term>
<listitem>
<para>
<replaceable class="parameter">checktime</replaceable> has two
possible values which specify the default time to check the
constraint.
<variablelist>
<varlistentry>
<term>IMMEDIATE</term>
<listitem>
<para>
Check constraint after each statement. This is the default.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>DEFERRED</term>
<listitem>
<para>
Check constraint only at the end of the transaction.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect3>
<refsect3 id="R3-SQL-REFERENCES-6">
<refsect3info>
<date>2000-02-04</date>
</refsect3info>
<title>
Outputs
</title>
<para>
<variablelist>
<varlistentry>
<term><replaceable>status</replaceable></term>
<listitem>
<para>
<variablelist>
<varlistentry>
<term><computeroutput>
ERROR: <replaceable class="parameter">name</replaceable> referential integrity violation - key referenced from
<replaceable class="parameter">table</replaceable> not found in <replaceable class="parameter">reftable</replaceable>
</computeroutput></term>
<listitem>
<para>
This error occurs at runtime if one tries to insert a value
into a column which does not have a matching column in the
referenced table.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect3>
<refsect3>
<title>Description</title>
<para>
The FOREIGN KEY constraint specifies a rule that a group of one
or more distinct columns of a table is related to a group
of distinct columns in the referenced table.
</para>
<para>
The FOREIGN KEY table constraint is similar to that for column
constraints, with the additional capability of encompassing
multiple columns.
</para>
<para>
Refer to the section on the FOREIGN KEY column constraint for more
information.
</para>
</refsect3>
</refsect2>
</refsect1>
<refsect1 id="R1-SQL-CREATETABLE-2">
<title>
Usage
</title>
<para>
Create table films and table distributors:
<programlisting>
CREATE TABLE films (
code CHARACTER(5) CONSTRAINT firstkey PRIMARY KEY,
title CHARACTER VARYING(40) NOT NULL,
did DECIMAL(3) NOT NULL,
date_prod DATE,
kind CHAR(10),
len INTERVAL HOUR TO MINUTE
);
</programlisting>
<programlisting>
CREATE TABLE distributors (
did DECIMAL(3) PRIMARY KEY DEFAULT NEXTVAL('serial'),
name VARCHAR(40) NOT NULL CHECK (name &lt;&gt; '')
);
</programlisting>
</para>
<para>
Create a table with a 2-dimensional array:
<programlisting>
CREATE TABLE array (
vector INT[][]
);
</programlisting>
</para>
<para> <para>
Define a UNIQUE table constraint for the table films. Define a primary key table constraint for the table
UNIQUE table constraints can be defined on one or more <structname>films</>. Primary key table constraints can be defined
columns of the table: on one or more columns of the table.
<programlisting> <programlisting>
CREATE TABLE films ( CREATE TABLE films (
code CHAR(5), code CHAR(5),
title VARCHAR(40), title VARCHAR(40),
did DECIMAL(3), did DECIMAL(3),
date_prod DATE, date_prod DATE,
kind CHAR(10), kind VARCHAR(10),
len INTERVAL HOUR TO MINUTE, len INTERVAL HOUR TO MINUTE,
CONSTRAINT production UNIQUE(date_prod) CONSTRAINT code_title PRIMARY KEY(code,title)
); );
</programlisting> </programlisting>
</para> </para>
<para> <para>
Define a CHECK column constraint: Define a primary key constraint for table
<structname>distributors</>. The following two examples are
equivalent, the first using the table constraint syntax, the second
the column constraint notation.
<programlisting> <programlisting>
CREATE TABLE distributors ( CREATE TABLE distributors (
did DECIMAL(3) CHECK (did > 100), did DECIMAL(3),
name CHAR VARYING(40),
PRIMARY KEY(did)
);
</programlisting>
<programlisting>
CREATE TABLE distributors (
did DECIMAL(3) PRIMARY KEY,
name VARCHAR(40) name VARCHAR(40)
); );
</programlisting> </programlisting>
</para> </para>
<para> <para>
Define a CHECK table constraint: This assigns a literal constant default value for the column
<literal>name</literal>, and arranges for the default value of
column <literal>did</literal> to be generated by selecting the next
value of a sequence object. The default value of
<literal>modtime</literal> will be the time at which the row is
inserted.
<programlisting> <programlisting>
CREATE TABLE distributors ( CREATE TABLE distributors (
did DECIMAL(3), name VARCHAR(40) DEFAULT 'luso films',
name VARCHAR(40) did INTEGER DEFAULT NEXTVAL('distributors_serial'),
CONSTRAINT con1 CHECK (did > 100 AND name > '') modtime TIMESTAMP DEFAULT CURRENT_TIMESTAMP
); );
</programlisting> </programlisting>
</para> </para>
<para> <para>
Define a PRIMARY KEY table constraint for the table films. Define two <literal>NOT NULL</> column constraints on the table
PRIMARY KEY table constraints can be defined on one or more <classname>distributors</classname>, one of which is explicitly
columns of the table: given a name:
<programlisting> <programlisting>
CREATE TABLE films ( CREATE TABLE distributors (
code CHAR(5), did DECIMAL(3) CONSTRAINT no_null NOT NULL,
title VARCHAR(40), name VARCHAR(40) NOT NULL
did DECIMAL(3),
date_prod DATE,
kind CHAR(10),
len INTERVAL HOUR TO MINUTE,
CONSTRAINT code_title PRIMARY KEY(code,title)
); );
</programlisting> </programlisting>
</para> </para>
<para> <para>
Defines a PRIMARY KEY column constraint for table distributors. Define a unique constraint for the <literal>name</literal> column:
PRIMARY KEY column constraints can only be defined on one column
of the table (the following two examples are equivalent):
<programlisting> <programlisting>
CREATE TABLE distributors ( CREATE TABLE distributors (
did DECIMAL(3), did DECIMAL(3),
name CHAR VARYING(40), name VARCHAR(40) UNIQUE
PRIMARY KEY(did)
); );
</programlisting> </programlisting>
The above is equivalent to the following specified as a table constraint:
<programlisting> <programlisting>
CREATE TABLE distributors ( CREATE TABLE distributors (
did DECIMAL(3) PRIMARY KEY, did DECIMAL(3),
name VARCHAR(40) name VARCHAR(40),
UNIQUE(name)
); );
</programlisting> </programlisting>
</para> </para>
</refsect1> </refsect1>
<refsect1 id="R1-SQL-CREATETABLE-3"> <refsect1 id="SQL-CREATETABLE-compatibility">
<title> <title id="SQL-CREATETABLE-compatibility-title">Compatibility</title>
Compatibility
</title>
<refsect2 id="R2-SQL-CREATETABLE-4">
<title>
SQL92
</title>
<para> <para>
In addition to the locally visible temporary table, SQL92 also defines a The <command>CREATE TABLE</command> conforms to SQL92 Intermediate
CREATE GLOBAL TEMPORARY TABLE statement, and optionally an and to a subset of SQL99, with exceptions listed below and in the
ON COMMIT clause: descriptions above.
<synopsis>
CREATE GLOBAL TEMPORARY TABLE <replaceable class="parameter">table</replaceable> ( <replaceable class="parameter">column</replaceable> <replaceable class="parameter">type</replaceable> [
DEFAULT <replaceable class="parameter">value</replaceable> ] [ CONSTRAINT <replaceable class="parameter">column_constraint</replaceable> ] [, ... ] )
[ CONSTRAINT <replaceable class="parameter">table_constraint</replaceable> ] [ ON COMMIT { DELETE | PRESERVE } ROWS ]
</synopsis>
</para> </para>
<para> <refsect2>
For temporary tables, the CREATE GLOBAL TEMPORARY TABLE statement <title>Temporary Tables</title>
names a new table visible to other clients and defines the table's columns
and constraints.
</para>
<para>
The optional ON COMMIT clause of CREATE TEMPORARY TABLE specifies
whether or not the temporary table should be emptied of rows
whenever COMMIT is executed. If the ON COMMIT clause is omitted, SQL92
specifies that the default is ON COMMIT DELETE ROWS. However,
<productname>Postgres</productname>' behavior is always like
ON COMMIT PRESERVE ROWS.
</para>
<refsect3 id="R3-SQL-UNIQUECLAUSE-1">
<title>
UNIQUE clause
</title>
<para>
SQL92 specifies some additional capabilities for UNIQUE:
</para>
<para> <para>
Table Constraint definition: In addition to the local temporary table, SQL92 also defines a
<literal>CREATE GLOBAL TEMPORARY TABLE</literal> statement.
<synopsis> Global temporary tables are also visible to other sessions.
[ CONSTRAINT <replaceable>constraint_name</replaceable> ] UNIQUE ( <replaceable>column</replaceable> [, ... ] )
[ { INITIALLY DEFERRED | INITIALLY IMMEDIATE } ]
[ [ NOT ] DEFERRABLE ]
</synopsis>
</para> </para>
<para> <para>
Column Constraint definition: For temporary tables, there is an optional <literal>ON COMMIT</literal> clause:
<synopsis>
CREATE { GLOBAL | LOCAL } TEMPORARY TABLE <replaceable class="parameter">table</replaceable> ( <replaceable class="parameter">...</replaceable> ) [ ON COMMIT { DELETE | PRESERVE } ROWS ]
</synopsis>
<synopsis> The <literal>ON COMMIT</literal> clause specifies whether or not
[ CONSTRAINT <replaceable>constraint_name</replaceable> ] UNIQUE the temporary table should be emptied of rows whenever
[ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ] <command>COMMIT</command> is executed. If the <literal>ON
[ [ NOT ] DEFERRABLE ] COMMIT</> clause is omitted, SQL92 specifies that the default is
</synopsis> <literal>ON COMMIT DELETE ROWS</>. However, the behavior of
<productname>PostgreSQL</productname> is always like <literal>ON
COMMIT PRESERVE ROWS</literal>.
</para> </para>
</refsect3> </refsect2>
<refsect3 id="R3-SQL-NULL-1"> <refsect2>
<title> <title><literal>NULL</literal> <quote>Constraint</quote></title>
NULL clause
</title>
<para>
The NULL <quote>constraint</quote> (actually a non-constraint) is a
<productname>Postgres</productname> extension to SQL92 that is
included for symmetry with the NOT NULL clause (and for compatibility
with some other RDBMSes). Since it is the
default for any column, its presence is simply noise.
<synopsis>
[ CONSTRAINT <replaceable>constraint_name</replaceable> ] NULL
</synopsis>
</para>
</refsect3>
<refsect3 id="R3-SQL-NOTNULL-4">
<title>
NOT NULL clause
</title>
<para> <para>
The <literal>NULL</> <quote>constraint</quote> (actually a
SQL92 specifies some additional capabilities for NOT NULL: non-constraint) is a <productname>PostgreSQL</productname>
<synopsis> extension to SQL92 that is included for compatibility with some
[ CONSTRAINT <replaceable>constraint_name</replaceable> ] NOT NULL other RDBMSes (and for symmetry with the <literal>NOT
[ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ] NULL</literal> constraint). Since it is the default for any
[ [ NOT ] DEFERRABLE ] column, its presence is simply noise.
</synopsis>
</para> </para>
</refsect3> </refsect2>
<!-- <refsect2>
I can't figure out why DEFAULT clause is different from what we already have. <title>Assertions</title>
Perhaps because CURRENT_USER and CURRENT_DATE have specific types (currently
the <type>name</type> type), if you aren't careful then the types won't match up with
the column. Not our problem...
- Thomas 1998-08-16
<REFSECT3 ID="R3-SQL-DEFAULTCLAUSE-1">
<TITLE>
DEFAULT clause
</TITLE>
<PARA>
SQL92 specifies some additional capabilities for the DEFAULT clause.
A DEFAULT clause is used to set the default value for a column
or a domain.
</para>
<synopsis>
DEFAULT niladic_user_function | niladic_datetime_function | NULL
</synopsis>
</refsect3>
-->
<refsect3 id="R3-SQL-CONSTRAINT-3">
<title>
CONSTRAINT clause
</title>
<para>
SQL92 specifies some additional capabilities for constraints,
and also defines assertions and domain constraints.
<note>
<para>
<productname>Postgres</productname> does not yet support
either domains or assertions.
</para>
</note>
</para>
<para> <para>
An assertion is a special type of integrity constraint and shares An assertion is a special type of integrity constraint and shares
the same namespace as other constraints. However, an assertion is the same namespace as other constraints. However, an assertion is
not necessarily dependent on one particular table as not necessarily dependent on one particular table as constraints
constraints are, so SQL-92 provides the CREATE ASSERTION statement are, so SQL92 provides the <command>CREATE ASSERTION</command>
as an alternate method for defining a constraint: statement as an alternate method for defining a constraint:
</para>
<synopsis> <synopsis>
CREATE ASSERTION <replaceable>name</replaceable> CHECK ( <replaceable>condition</replaceable> ) CREATE ASSERTION <replaceable>name</replaceable> CHECK ( <replaceable>condition</replaceable> )
</synopsis> </synopsis>
</para>
<para>
<productname>PostgreSQL</> does not implement assertions at present.
</para>
</refsect2>
<!--
<para> <para>
Domain constraints are defined by CREATE DOMAIN or ALTER DOMAIN Domain constraints are defined by CREATE DOMAIN or ALTER DOMAIN
statements: statements:
...@@ -1984,191 +830,38 @@ CREATE ASSERTION <replaceable>name</replaceable> CHECK ( <replaceable>condition< ...@@ -1984,191 +830,38 @@ CREATE ASSERTION <replaceable>name</replaceable> CHECK ( <replaceable>condition<
[ [ NOT ] DEFERRABLE ] [ [ NOT ] DEFERRABLE ]
</synopsis> </synopsis>
</para> </para>
-->
<para> <refsect2>
Table constraint definition: <title>Inheritance</title>
<synopsis>
[ CONSTRAINT <replaceable>constraint_name</replaceable> ] { PRIMARY KEY ( <replaceable class="parameter">column</replaceable>, ... ) | FOREIGN KEY <replaceable>constraint</replaceable> | UNIQUE <replaceable>constraint</replaceable> | CHECK <replaceable>constraint</replaceable> }
[ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
[ [ NOT ] DEFERRABLE ]
</synopsis>
</para>
<para>
Column constraint definition:
<synopsis>
[ CONSTRAINT <replaceable>constraint_name</replaceable> ] { NOT NULL | PRIMARY KEY | FOREIGN KEY <replaceable>constraint</replaceable> | UNIQUE | CHECK <replaceable>constraint</replaceable> }
[ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
[ [ NOT ] DEFERRABLE ]
</synopsis>
</para>
<para> <para>
A CONSTRAINT definition may contain one deferment attribute Multiple inheritance via the <literal>INHERITS</literal> clause is
clause and/or one initial constraint mode clause, in any order. a <productname>PostgreSQL</productname> language extension. SQL99
<variablelist> (but not SQL92) defines single inheritance using a different
<varlistentry> syntax and different semantics. SQL99-style inheritance is not
<term>NOT DEFERRABLE</term> yet supported by <productname>PostgreSQL</productname>.
<listitem>
<para>
The constraint must be checked at the end of each statement.
SET CONSTRAINTS ALL DEFERRED will have no effect on this type
of constraint.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>DEFERRABLE</term>
<listitem>
<para>
This controls whether the constraint can be deferred to the end
of the transaction. If SET CONSTRAINTS ALL DEFERRED is used or
the constraint is set to INITIALLY DEFERRED, this will cause
the foreign key to be checked only at the end of the
transaction.
</para>
<note>
<para>
<command>SET CONSTRAINTS</> changes the foreign key constraint mode
only for the current transaction.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term>INITIALLY IMMEDIATE</term>
<listitem>
<para>
Check constraint after each statement. This is the default.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>INITIALLY DEFERRED</term>
<listitem>
<para>
Check constraint only at the end of the transaction.
</para>
</listitem>
</varlistentry>
</variablelist>
</para> </para>
</refsect3> </refsect2>
<refsect3 id="R3-SQL-CHECK-4"> <refsect2>
<title> <title>Object IDs</title>
CHECK clause
</title>
<para>
SQL92 specifies some additional capabilities for CHECK in either
table or column constraints.
</para>
<!--
Constraints associated with domains do not need to be mentioned here,
even though it is the case that a domain constraint may possibly
affect a column or a table.
- Thomas 1998-08-16
<para>
A CHECK constraint is either a table constraint, a column
constraint or a domain constraint.
</para>
-->
<para>
table constraint definition:
<synopsis>
[ CONSTRAINT <replaceable>constraint_name</replaceable> ]
CHECK ( VALUE <replaceable>condition</replaceable> )
[ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
[ [ NOT ] DEFERRABLE ]
</synopsis>
</para>
<para> <para>
column constraint definition: The <productname>PostgreSQL</productname> concept of OIDs is not
<synopsis> standard.
[ CONSTRAINT <replaceable>constraint_name</replaceable> ]
CHECK ( VALUE <replaceable>condition</replaceable> )
[ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
[ [ NOT ] DEFERRABLE ]
</synopsis>
</para>
<!--
<para>
domain constraint definition:
</para>
<synopsis>
[ CONSTRAINT name]
CHECK ( VALUE condition )
[ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
[ [ NOT ] DEFERRABLE ]
</synopsis>
<para>
CHECK domain constraints can be defined in either
a CREATE DOMAIN statement or an ALTER DOMAIN statement:
</para> </para>
<programlisting> </refsect2>
CREATE DOMAIN duration AS SMALLINT </refsect1>
CONSTRAINT minutes CHECK (VALUE IN (90,120,180,240));
ALTER DOMAIN cities
ADD CONSTRAINT new_city CHECK (VALUE LIKE 'L%');
</programlisting>
-->
</refsect3>
<refsect3 id="R3-SQL-PRIMARYKEY-1">
<title>
PRIMARY KEY clause
</title>
<para>
SQL92 specifies some additional capabilities for PRIMARY KEY:
</para>
<para>
Table Constraint definition:
<synopsis>
[ CONSTRAINT <replaceable>constraint_name</replaceable> ] PRIMARY KEY ( <replaceable>column</replaceable> [, ... ] )
[ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
[ [ NOT ] DEFERRABLE ]
</synopsis>
</para>
<para>
Column Constraint definition:
<synopsis>
[ CONSTRAINT <replaceable>constraint_name</replaceable> ] PRIMARY KEY
[ {INITIALLY DEFERRED | INITIALLY IMMEDIATE} ]
[ [ NOT ] DEFERRABLE ]
</synopsis>
</para>
</refsect3>
<refsect3 id="R3-SQL-INHERITANCE-1"> <refsect1>
<title> <title>See Also</title>
Inheritance
</title>
<para>
Multiple inheritance via the INHERITS clause is a
<productname>Postgres</productname> language extension.
SQL99 (but not SQL92) defines single inheritance using a different
syntax and different semantics. SQL99-style inheritance is not yet
supported by <productname>Postgres</productname>.
</para>
</refsect3>
<refsect3 id="R3-SQL-OBJECTIDS-1"> <simplelist type="inline">
<title> <member><xref linkend="sql-altertable"></member>
Object IDs <member><xref linkend="sql-droptable"></member>
</title> </simplelist>
<para>
The <productname>Postgres</productname> concept of OIDs is not
standard. SQL99 (but not SQL92) has a notion of object ID, but
the syntax and semantics are different --- SQL99 associates OIDs
with individual values, not with rows.
</para>
</refsect3>
</refsect2>
</refsect1> </refsect1>
</refentry> </refentry>
......
doc/src/sgml/ref/create_table_as.sgml
View file @ f08c9ff8
<!-- <!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_table_as.sgml,v 1.7 2001/09/03 12:57:49 petere Exp $ $Header: /cvsroot/pgsql/doc/src/sgml/ref/create_table_as.sgml,v 1.8 2001/10/22 18:14:47 petere Exp $
Postgres documentation Postgres documentation
--> -->
<refentry id="SQL-CREATETABLEAS"> <refentry id="SQL-CREATETABLEAS">
<refmeta> <refmeta>
<refentrytitle id="SQL-CREATETABLEAS-TITLE"> <refentrytitle>CREATE TABLE AS</refentrytitle>
CREATE TABLE AS
</refentrytitle>
<refmiscinfo>SQL - Language Statements</refmiscinfo> <refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta> </refmeta>
<refnamediv> <refnamediv>
<refname> <refname>CREATE TABLE AS</refname>
CREATE TABLE AS <refpurpose>create a new table from the results of a query</refpurpose>
</refname>
<refpurpose>
create a new table from the results of a query
</refpurpose>
</refnamediv> </refnamediv>
<refsynopsisdiv> <refsynopsisdiv>
<refsynopsisdivinfo> <synopsis>
<date>2001-03-03</date> CREATE [ [ LOCAL ] { TEMPORARY | TEMP } ] TABLE <replaceable>table_name</replaceable> [ (<replaceable>column_name</replaceable> [, ...] ) ]
</refsynopsisdivinfo> AS <replaceable>query</replaceable>
<synopsis>
CREATE [ TEMPORARY | TEMP ] TABLE <replaceable>table</replaceable> [ (<replaceable>column</replaceable> [, ...] ) ]
AS <replaceable>select_clause</replaceable>
</synopsis> </synopsis>
</refsynopsisdiv>
<refsect2> <refsect1>
<refsect2info> <refsect1info>
<date>1998-09-22</date> <date>2001-03-20</date>
</refsect2info> </refsect1info>
<title> <title>
Inputs Description
</title> </title>
<para> <para>
<command>CREATE TABLE AS</command> creates a table and fills it
with data computed by a <command>SELECT</command> command. The
table columns have the names and data types associated with the
output columns of the <command>SELECT</command> (except that you
can override the column names by giving an explicit list of new
column names).
</para>
<para>
<command>CREATE TABLE AS</command> bears some resemblance to
creating a view, but it is really quite different: it creates a new
table and evaluates the query just once to fill the new table
initially. The new table will not track subsequent changes to the
source tables of the query. In contrast, a view re-evaluates the
underlying <command>SELECT</command> statements whenever it is
queried.
</para>
</refsect1>
<refsect1>
<title>Parameters</title>
<variablelist> <variablelist>
<varlistentry> <varlistentry>
<term>TEMPORARY or TEMP</term> <term><literal>[LOCAL] TEMPORARY</> or <literal>[LOCAL] TEMP</></term>
<listitem> <listitem>
<para> <para>
If specified, the table is created only within this session, and is If specified, the table is created as a temporary table.
automatically dropped on session exit. Temporary tables are automatically dropped at the end of a
Existing permanent tables with the same name are not visible session. Existing persistent tables with the same name are not
(in this session) while the temporary table exists. visible to the current session while the temporary table exists.
Any indexes created on a temporary table are automatically Any indexes created on a temporary table are automatically
temporary as well. temporary as well.
</para> </para>
<para>
The <literal>LOCAL</literal> word is optional.
</para>
</listitem> </listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
<term><replaceable>table</replaceable></term> <term><replaceable>table_name</replaceable></term>
<listitem> <listitem>
<para> <para>
The name of the new table to be created. The name of the new table to be created. This table must not
This table must not already exist. However, a temporary table already exist. However, a temporary table can be created that
can be created that has the same name as an existing permanent has the same name as an existing permanent table.
table.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
<term><replaceable>column</replaceable></term> <term><replaceable>column_name</replaceable></term>
<listitem> <listitem>
<para> <para>
The name of a column. Multiple column names can be specified using The name of a column in the new table. Multiple column names can
a comma-delimited list of column names. If column names are not be specified using a comma-delimited list of column names. If
provided, they are taken from the output column names of the column names are not provided, they are taken from the output
SELECT query. column names of the query.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
<varlistentry> <varlistentry>
<term><replaceable>select_clause</replaceable></term> <term><replaceable>query</replaceable></term>
<listitem> <listitem>
<para> <para>
A valid query statement. Refer to A query statement (that is, a <command>SELECT</command>
<xref linkend="sql-select" endterm="sql-select-title"> command). Refer to
<xref linkend="sql-select">
for a description of the allowed syntax. for a description of the allowed syntax.
</para> </para>
</listitem> </listitem>
</varlistentry> </varlistentry>
</variablelist> </variablelist>
</para> </refsect1>
</refsect2>
<refsect2> <refsect1>
<refsect2info> <title>Diagnostics</title>
<date>1998-09-22</date>
</refsect2info>
<title>
Outputs
</title>
<para> <para>
Refer to Refer to <xref linkend="sql-createtable"> and
<xref linkend="sql-createtable" endterm="sql-createtable-title"> <xref linkend="sql-select">
and
<xref linkend="sql-select" endterm="sql-select-title">
for a summary of possible output messages. for a summary of possible output messages.
</para> </para>
</refsect2> </refsect1>
</refsynopsisdiv>
<refsect1> <refsect1>
<refsect1info> <title>Notes</title>
<date>2001-03-20</date>
</refsect1info>
<title>
Description
</title>
<para> <para>
<command>CREATE TABLE AS</command> creates a table and fills it This command is functionally equivalent to <xref
with data computed by a <command>SELECT</command> command. The linkend="sql-selectinto">, but it is preferred since it is less
table columns have the names and datatypes associated with the likely to be confused with other uses of the <command>SELECT
output columns of the <command>SELECT</command> (except that you ... INTO</command> syntax.
can override the <command>SELECT</command> column names by giving
an explicit list of column names).
</para> </para>
</refsect1>
<refsect1>
<title>Compatibility</title>
<para> <para>
<command>CREATE TABLE AS</command> bears some resemblance to creating This command is modeled after an <productname>Oracle</productname>
a view, but it is really quite different: it creates a new table and feature. There is no command with equivalent functionality in
evaluates the <command>SELECT</command> just once to fill the new table SQL92 or SQL99. However, a combination of <literal>CREATE
initially. The new table will not track subsequent changes to TABLE</literal> and <literal>INSERT ... SELECT</literal> can
the source tables of the <command>SELECT</command>. In contrast, accomplish the same thing with little more effort.
a view re-evaluates the given <command>SELECT</command> whenever queried.
</para> </para>
</refsect1>
<refsect1>
<title>History</title>
<para> <para>
This command is functionally equivalent to The <command>CREATE TABLE AS</command> command has been available
<xref linkend="sql-selectinto" endterm="sql-selectinto-title">, since <productname>PostgreSQL</productname> 6.3.
but it is preferred since it is less likely to be confused with
other uses of the <command>SELECT ... INTO</command> syntax.
</para> </para>
</refsect1> </refsect1>
<refsect1>
<title>See Also</title>
<simplelist type="inline">
<member><xref linkend="sql-createtable"></member>
<member><xref linkend="sql-createview"></member>
<member><xref linkend="sql-select"></member>
<member><xref linkend="sql-selectinto"></member>
</simplelist>
</refsect1>
</refentry> </refentry>
<!-- Keep this comment at the end of the file <!-- Keep this comment at the end of the file
......
doc/src/sgml/ref/select_into.sgml
View file @ f08c9ff8
<!-- <!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/select_into.sgml,v 1.12 2001/09/23 13:34:44 momjian Exp $ $Header: /cvsroot/pgsql/doc/src/sgml/ref/select_into.sgml,v 1.13 2001/10/22 18:14:47 petere Exp $
Postgres documentation Postgres documentation
--> -->
...@@ -89,7 +89,7 @@ where <replaceable class="PARAMETER">from_item</replaceable> can be: ...@@ -89,7 +89,7 @@ where <replaceable class="PARAMETER">from_item</replaceable> can be:
<para> <para>
All other inputs are described in detail for All other inputs are described in detail for
<xref linkend="sql-select" endterm="sql-select-title">. <xref linkend="sql-select">.
</para> </para>
</refsect2> </refsect2>
...@@ -103,9 +103,9 @@ where <replaceable class="PARAMETER">from_item</replaceable> can be: ...@@ -103,9 +103,9 @@ where <replaceable class="PARAMETER">from_item</replaceable> can be:
<para> <para>
Refer to Refer to
<xref linkend="sql-createtable" endterm="sql-createtable-title"> <xref linkend="sql-createtable">
and and
<xref linkend="sql-select" endterm="sql-select-title"> <xref linkend="sql-select">
for a summary of possible output messages. for a summary of possible output messages.
</para> </para>
</refsect2> </refsect2>
...@@ -128,7 +128,7 @@ where <replaceable class="PARAMETER">from_item</replaceable> can be: ...@@ -128,7 +128,7 @@ where <replaceable class="PARAMETER">from_item</replaceable> can be:
<note> <note>
<para> <para>
<xref linkend="sql-createtableas" endterm="sql-createtableas-title"> <xref linkend="sql-createtableas">
is functionally equivalent to <command>SELECT INTO</command>. is functionally equivalent to <command>SELECT INTO</command>.
<command>CREATE TABLE AS</command> is the recommended syntax, since <command>CREATE TABLE AS</command> is the recommended syntax, since
<command>SELECT INTO</command> is not standard. In fact, this form of <command>SELECT INTO</command> is not standard. In fact, this form of
......
doc/src/sgml/stylesheet.dsl
View file @ f08c9ff8
<!-- $Header: /cvsroot/pgsql/doc/src/sgml/stylesheet.dsl,v 1.14 2001/10/09 18:46:00 petere Exp $ --> <!-- $Header: /cvsroot/pgsql/doc/src/sgml/stylesheet.dsl,v 1.15 2001/10/22 18:14:47 petere Exp $ -->
<!DOCTYPE style-sheet PUBLIC "-//James Clark//DTD DSSSL Style Sheet//EN" [ <!DOCTYPE style-sheet PUBLIC "-//James Clark//DTD DSSSL Style Sheet//EN" [
<!-- must turn on one of these with -i on the jade command line --> <!-- must turn on one of these with -i on the jade command line -->
...@@ -123,6 +123,16 @@ ...@@ -123,6 +123,16 @@
;;; XXX The above is very ugly. It might be better to run 'tidy' on ;;; XXX The above is very ugly. It might be better to run 'tidy' on
;;; the resulting *.html files. ;;; the resulting *.html files.
;; Format multiple terms in varlistentry vertically, instead
;; of comma-separated.
(element (varlistentry term)
(make sequence
(process-children-trim)
(if (not (last-sibling?))
(make empty-element gi: "BR")
(empty-sosofo))))
]]> <!-- %output-html --> ]]> <!-- %output-html -->
<![ %output-print; [ <![ %output-print; [
......
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