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Postgres FD Implementation
Commit 95af0cb9 authored by Thomas G. Lockhart's avatar Thomas G. Lockhart
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Fix Postgres to support SQL92 syntax. Old syntax still works too.

parent 4dce924b
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doc/src/sgml/ref/declare.sgml
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doc/src/sgml/ref/fetch.sgml
View file @ 95af0cb9
......@@ -17,7 +17,9 @@ Gets rows using a cursor
<DATE>1998-09-01</DATE>
</REFSYNOPSISDIVINFO>
<SYNOPSIS>
FETCH [ <REPLACEABLE CLASS="PARAMETER">selector</REPLACEABLE> ] { [ <REPLACEABLE CLASS="PARAMETER">#</REPLACEABLE> | ALL ] } { IN | FROM } <REPLACEABLE CLASS="PARAMETER">cursor</REPLACEABLE>
FETCH [ <REPLACEABLE CLASS="PARAMETER">selector</REPLACEABLE> ] [ <REPLACEABLE CLASS="PARAMETER">count</REPLACEABLE> ]
{ IN | FROM } <REPLACEABLE CLASS="PARAMETER">cursor</REPLACEABLE>
FETCH [ RELATIVE ] [ { [ <REPLACEABLE CLASS="PARAMETER">#</REPLACEABLE> | ALL | NEXT | PRIOR ] } ] FROM ] <REPLACEABLE CLASS="PARAMETER">cursor</REPLACEABLE>
</SYNOPSIS>
<REFSECT2 ID="R2-SQL-FETCH-1">
......@@ -36,7 +38,8 @@ Inputs
</TERM>
<LISTITEM>
<PARA>
Selector define fetch direction and it can be one
<REPLACEABLE CLASS="PARAMETER">selector</REPLACEABLE>
defines the fetch direction. It can be one
the following:
<VARIABLELIST>
......@@ -46,8 +49,8 @@ FORWARD
</TERM>
<LISTITEM>
<PARA>
fetch next row(s), it is assumed by default
if selector is omitted.
fetch next row(s). This is the default
if <REPLACEABLE CLASS="PARAMETER">selector</REPLACEABLE> is omitted.
<VARLISTENTRY>
<TERM>
......@@ -57,15 +60,35 @@ BACKWARD
<PARA>
fetch previous row(s).
<VARLISTENTRY>
<TERM>
RELATIVE
</TERM>
<LISTITEM>
<PARA>
Noise word for SQL92 compatibility.
</VARIABLELIST>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER">count</REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>
<REPLACEABLE CLASS="PARAMETER">count</REPLACEABLE>
determines how many rows to fetch. It can be one of the following:
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER">#</REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>
An unsigned integer that specify how many rows to fetch.
A signed integer that specify how many rows to fetch.
Note that a negative integer is equivalent to changing the sense of
FORWARD and BACKWARD.
<VARLISTENTRY>
<TERM>
......@@ -75,6 +98,24 @@ ALL
<PARA>
Retrieve all remaining rows.
<VARLISTENTRY>
<TERM>
NEXT
</TERM>
<LISTITEM>
<PARA>
Equivalent to specifying a count of <command>1</command>.
<VARLISTENTRY>
<TERM>
PRIOR
</TERM>
<LISTITEM>
<PARA>
Equivalent to specifying a count of <command>-1</command>.
</VARIABLELIST>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER">cursor</REPLACEABLE>
......@@ -108,6 +149,34 @@ NOTICE: PerformPortalFetch: portal "<REPLACEABLE CLASS="PARAMETER">cursor</REPL
If <REPLACEABLE CLASS="PARAMETER">cursor</REPLACEABLE> is not previously declared.
The cursor must be declared within a transaction block.
<VARLISTENTRY>
<TERM>
NOTICE: FETCH/ABSOLUTE not supported, using RELATIVE
</TERM>
<LISTITEM>
<PARA>
<productname>Postgres</productname> does not support absolute
positioning of cursors.
<VARLISTENTRY>
<TERM>
ERROR: FETCH/RELATIVE at current position is not supported
</TERM>
<LISTITEM>
<PARA>
<acronym>SQL92</acronym> allows one to repetatively retrieve the cursor
at its "current position" using the syntax
<programlisting>
FETCH RELATIVE 0 FROM <REPLACEABLE CLASS="PARAMETER">cursor</REPLACEABLE>
</programlisting>
<productname>Postgres</productname> does not currently support
this notion; in fact the value zero is reserved to indicate that
all rows should be retrieved and is equivalent to specifying the ALL keyword.
If the RELATIVE keyword has been used, the <productname>Postgres</productname>
assumes that the user intended <acronym>SQL92</acronym> behavior
and returns this error message.
</variablelist>
</REFSECT2>
......@@ -122,13 +191,30 @@ Description
</TITLE>
<PARA>
FETCH allows a user to retrieve rows using a cursor.
The number of rows retrieved is specified by #.
The number of rows retrieved is specified by
<REPLACEABLE CLASS="PARAMETER">#</REPLACEABLE>.
If the number of rows remaining in the cursor is less
than #, then only those available are fetched.
than <REPLACEABLE CLASS="PARAMETER">#</REPLACEABLE>,
then only those available are fetched.
Substituting the keyword ALL in place of a number will
cause all remaining rows in the cursor to be retrieved.
Instances may be fetched in both forward and backward
directions. The default direction is forward.
Instances may be fetched in both FORWARD and BACKWARD
directions. The default direction is FORWARD.
<tip>
<para>
Negative numbers are now allowed to be specified for the
row count. A negative number is equivalent to reversing
the sense of the FORWARD and BACKWARD keywords. For example,
<command>FORWARD -1</command> is the same as <command>BACKWARD 1</command>.
</tip>
<para>
Note that the FORWARD and BACKWARD keywords are
<productname>Postgres</productname> extensions.
The <acronym>SQL92</acronym> syntax is also supported, specified
in the second form of the command. See below for details
on compatibility issues.
<para>
Once all rows are fetched, every other fetch access returns
......@@ -138,8 +224,9 @@ Description
Updating data in a cursor is not supported by
<productname>Postgres</productname>,
because mapping cursor updates back to base tables is
not generally possible, similarly to VIEW updates. Consequently,
users must issue explicit replace commands to update data.
not generally possible, as is also the case with VIEW updates.
Consequently,
users must issue explicit UPDATE commands to replace data.
<para>
Cursors may only be used inside of transactions because
......@@ -216,87 +303,25 @@ Compatibility
SQL92
</TITLE>
<PARA>
SQL92 specifies some additional capabilities for FETCH statement.
SQL92 allows absolute positioning of the cursor for
FETCH, and allows placing the results into explicit variables.
<synopsis>
FETCH [ [ <REPLACEABLE CLASS="PARAMETER">selector</REPLACEABLE> ] FROM ] <REPLACEABLE CLASS="PARAMETER">cursor</REPLACEABLE>
FETCH ABSOLUTE <REPLACEABLE CLASS="PARAMETER">#</REPLACEABLE>
FROM <REPLACEABLE CLASS="PARAMETER">cursor</REPLACEABLE>
INTO :<REPLACEABLE CLASS="PARAMETER">variable</REPLACEABLE> [, ...]
</synopsis>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER">selector</REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>
Defines the fetch direction with one of the following values:
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
NEXT
</TERM>
<LISTITEM>
<PARA>
Fetch next row, it is assumed by default
if selector is omitted.
This is the only legal selector unless cursor is
declared with the SCROLL option.
<VARLISTENTRY>
<TERM>
PRIOR
</TERM>
<LISTITEM>
<PARA>
Fetch previous row.
<VARLISTENTRY>
<TERM>
FIRST
</TERM>
<LISTITEM>
<PARA>
Fetch first row.
<VARLISTENTRY>
<TERM>
LAST
</TERM>
<LISTITEM>
<PARA>
Fetch last row.
<VARLISTENTRY>
<TERM>
ABSOLUTE <REPLACEABLE CLASS="PARAMETER">#</REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>
Refers to the <REPLACEABLE CLASS="PARAMETER">#</REPLACEABLE>th row
in the table associated with the cursor.
<VARLISTENTRY>
<TERM>
RELATIVE <REPLACEABLE CLASS="PARAMETER">#</REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>
Refers to the <REPLACEABLE CLASS="PARAMETER">#</REPLACEABLE>th row
relative to the cursor position.
A negative number is equivalent to reversing the sense of the FORWARD and
BACKWARD keywords.
</variablelist>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER">cursor</REPLACEABLE>
ABSOLUTE
</TERM>
<LISTITEM>
<PARA>
A cursor previously defined in the same transaction block using BEGIN and DECLARE.
The cursor should be positioned to the specified absolute
row number. All row numbers in <productname>Postgres</productname>
are relative numbers so this capability is not supported.
<VARLISTENTRY>
<TERM>
......
doc/src/sgml/ref/move.sgml
View file @ 95af0cb9
......@@ -18,105 +18,11 @@ Moves cursor position
<DATE>1998-09-01</DATE>
</REFSYNOPSISDIVINFO>
<SYNOPSIS>
MOVE [ <REPLACEABLE CLASS="PARAMETER">selector</REPLACEABLE> ] { [ <REPLACEABLE CLASS="PARAMETER">#</REPLACEABLE> | ALL ] } IN <REPLACEABLE CLASS="PARAMETER">cursor</REPLACEABLE>
MOVE [ <REPLACEABLE CLASS="PARAMETER">selector</REPLACEABLE> ] [ <REPLACEABLE CLASS="PARAMETER">count</REPLACEABLE> ]
{ IN | FROM } <REPLACEABLE CLASS="PARAMETER">cursor</REPLACEABLE>
FETCH [ RELATIVE ] [ { [ <REPLACEABLE CLASS="PARAMETER">#</REPLACEABLE> | ALL | NEXT | PRIOR ] } ] FROM ] <REPLACEABLE CLASS="PARAMETER">cursor</REPLACEABLE>
</SYNOPSIS>
<REFSECT2 ID="R2-SQL-MOVE-1">
<REFSECT2INFO>
<DATE>1998-09-01</DATE>
</REFSECT2INFO>
<TITLE>
Inputs
</TITLE>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER">selector</REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>
<variablelist>
<varlistentry>
<term>
FORWARD
</term>
<listitem>
<para>
Skip next row(s), it is assumed by default
if selector is omitted.
<varlistentry>
<term>
BACKWARD
</term>
<listitem>
<para>
Skip previous row(s).
</variablelist>
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER">#</REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>
An unsigned integer that specify how many rows to skip.
<VARLISTENTRY>
<TERM>
ALL
</TERM>
<LISTITEM>
<PARA>
Skip all remaining rows.
<VARLISTENTRY>
<TERM>
<REPLACEABLE CLASS="PARAMETER">cursor</REPLACEABLE>
</TERM>
<LISTITEM>
<PARA>
An open cursor's name.
</VARIABLELIST>
</REFSECT2>
<REFSECT2 ID="R2-SQL-MOVE-2">
<REFSECT2INFO>
<DATE>1998-09-01</DATE>
</REFSECT2INFO>
<TITLE>
Outputs
</TITLE>
<PARA>
</PARA>
<VARIABLELIST>
<VARLISTENTRY>
<TERM>
MOVE
</TERM>
<LISTITEM>
<PARA>
Message returned if successfully.
<VARLISTENTRY>
<TERM>
NOTICE: PerformPortalFetch: portal <REPLACEABLE CLASS="PARAMETER">cursor</REPLACEABLE> not found.
</TERM>
<LISTITEM>
<PARA>
If cursor is not declared.
</VARIABLELIST>
</REFSECT2>
</REFSYNOPSISDIV>
<REFSECT1 ID="R1-SQL-MOVE-1">
<REFSECT1INFO>
<DATE>1998-04-15</DATE>
......@@ -125,9 +31,13 @@ NOTICE: PerformPortalFetch: portal <REPLACEABLE CLASS="PARAMETER">cursor</REPLA
Description
</TITLE>
<PARA>
MOVE allows a user to move cursor position for specified
number of rows. MOVE works like fetch command: it
fetches rows, but put them nowhere.
MOVE allows a user to move cursor position a specified
number of rows. MOVE works like the FETCH command, but only
positions the cursor and does
not return rows.
<para>
Refer to the FETCH command for details on syntax and usage.
<REFSECT2 ID="R2-SQL-MOVE-3">
<REFSECT2INFO>
......@@ -140,9 +50,9 @@ Notes
MOVE is a <productname>Postgres</productname> language extension.
<para>
Refer to FETCH statements for further description
Refer to FETCH for a description
of valid arguments.
Refer to DECLARE statements to declare a cursor.
Refer to DECLARE to declare a cursor.
Refer to BEGIN WORK, COMMIT WORK, ROLLBACK WORK statements
for further information about transactions.
......@@ -195,5 +105,6 @@ Compatibility
SQL92
</TITLE>
<PARA>
There is no SQL92 MOVE statement.
There is no SQL92 MOVE statement. Instead, <acronym>SQL92</acronym> allows
one to FETCH rows from an absolute cursor position.
</REFENTRY>
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