<title>Pattern Matching with <function>LIKE</function></title>
<indexterm>
<primary>like</primary>
</indexterm>
<synopsis>
<replaceable>string</replaceable> LIKE <replaceable>pattern</replaceable> <optional> ESCAPE <replaceable>escape-character</replaceable> </optional>
<replaceable>string</replaceable> NOT LIKE <replaceable>pattern</replaceable> <optional> ESCAPE <replaceable>escape-character</replaceable> </optional>
@@ -145,6 +153,11 @@ FROM <replaceable>table_reference</replaceable> <optional>, <replaceable>table_r
<term>Qualified JOINs</term>
<listitem>
<indexterm>
<primary>joins</primary>
<secondary>outer</secondary>
</indexterm>
<synopsis>
<replaceable>T1</replaceable> { <optional>INNER</optional> | { LEFT | RIGHT | FULL } <optional>OUTER</optional> } JOIN <replaceable>T2</replaceable> ON <replaceable>boolean_expression</replaceable>
<replaceable>T1</replaceable> { <optional>INNER</optional> | { LEFT | RIGHT | FULL } <optional>OUTER</optional> } JOIN <replaceable>T2</replaceable> USING ( <replaceable>join column list</replaceable> )
...
...
@@ -187,6 +200,10 @@ FROM <replaceable>table_reference</replaceable> <optional>, <replaceable>table_r
</para>
<para>
<indexterm>
<primary>joins</primary>
<secondary>natural</secondary>
</indexterm>
Finally, NATURAL is a shorthand form of USING: it forms a USING
list consisting of exactly those column names that appear in both
input tables. As with USING, these columns appear only once in
...
...
@@ -213,6 +230,11 @@ FROM <replaceable>table_reference</replaceable> <optional>, <replaceable>table_r
<term>LEFT OUTER JOIN</term>
<listitem>
<indexterm>
<primary>joins</primary>
<secondary>left</secondary>
</indexterm>
<para>
First, an INNER JOIN is performed. Then, for each row in T1
that does not satisfy the join condition with any row in
...
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@@ -268,6 +290,10 @@ FROM <replaceable>table_reference</replaceable> <optional>, <replaceable>table_r
<sect3 id="queries-subqueries">
<title>Subqueries</title>
<indexterm zone="queries-subqueries">
<primary>subqueries</primary>
</indexterm>
<para>
Subqueries specifying a derived table must be enclosed in
parentheses and <emphasis>must</emphasis> be named using an AS
...
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@@ -289,6 +315,16 @@ FROM (SELECT * FROM table1) AS alias_name
<sect3 id="queries-table-aliases">
<title>Table and Column Aliases</title>
<indexterm zone="queries-table-aliases">
<primary>label</primary>
<secondary>table</secondary>
</indexterm>
<indexterm>
<primary>alias</primary>
<see>label</see>
</indexterm>
<para>
A temporary name can be given to tables and complex table
references to be used for references to the derived table in
...
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@@ -400,6 +436,10 @@ FROM (SELECT * FROM T1) DT1, T2, T3
<sect2 id="queries-where">
<title>WHERE clause</title>
<indexterm zone="queries-where">
<primary>where</primary>
</indexterm>
<para>
The syntax of the WHERE clause is
<synopsis>
...
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@@ -482,6 +522,10 @@ FROM FDT WHERE
<sect2 id="queries-group">
<title>GROUP BY and HAVING clauses</title>
<indexterm zone="queries-group">
<primary>group</primary>
</indexterm>
<para>
After passing the WHERE filter, the derived input table may be
subject to grouping, using the GROUP BY clause, and elimination of
...
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@@ -578,6 +622,11 @@ SELECT pid AS "Products",
<sect1 id="queries-select-lists">
<title>Select Lists</title>
<indexterm>
<primary>select</primary>
<secondary>select list</secondary>
</indexterm>
<para>
As shown in the previous section,
the table expression in the <command>SELECT</command> command
...
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@@ -620,6 +669,11 @@ SELECT tbl1.a, tbl2.b, tbl1.c FROM ...
<sect2 id="queries-column-labels">
<title>Column Labels</title>
<indexterm zone="queries-column-labels">
<primary>label</primary>
<secondary>column</secondary>
</indexterm>
<para>
The entries in the select list can be assigned names for further
processing. The <quote>further processing</quote> in this case is
...
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@@ -652,6 +706,10 @@ SELECT a AS value, b + c AS sum FROM ...
<sect2 id="queries-distinct">
<title>DISTINCT</title>
<indexterm zone="queries-distinct">
<primary>distinct</primary>
</indexterm>
<para>
After the select list has been processed, the result table may
optionally be subject to the elimination of duplicates. The
...
...
@@ -700,6 +758,16 @@ SELECT DISTINCT ON (<replaceable>expression</replaceable> <optional>, <replaceab
<sect1 id="queries-union">
<title>Combining Queries</title>
<indexterm zone="queries-union">
<primary>union</primary>
</indexterm>
<indexterm zone="queries-union">
<primary>intersection</primary>
</indexterm>
<indexterm zone="queries-union">
<primary>except</primary>
</indexterm>
<para>
The results of two queries can be combined using the set operations
union, intersection, and difference. The syntax is
...
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@@ -757,6 +825,11 @@ SELECT DISTINCT ON (<replaceable>expression</replaceable> <optional>, <replaceab
<sect1 id="queries-order">
<title>Sorting Rows</title>
<indexterm zone="queries-order">
<primary>sorting</primary>
<secondary>query results</secondary>
</indexterm>
<para>
After a query has produced an output table (after the select list
has been processed) it can optionally be sorted. If sorting is not
...
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@@ -817,6 +890,15 @@ SELECT a AS b FROM table1 ORDER BY a;
<sect1 id="queries-limit">
<title>LIMIT and OFFSET</title>
<indexterm zone="queries-limit">
<primary>limit</primary>
</indexterm>
<indexterm zone="queries-limit">
<primary>offset</primary>
<secondary>with query results</secondary>
</indexterm>
<synopsis>
SELECT <replaceable>select_list</replaceable> FROM <replaceable>table_expression</replaceable> <optional>ORDER BY <replaceable>sort_spec</replaceable></optional> <optional>LIMIT { <replaceable>number</replaceable> | ALL }</optional> <optional>OFFSET <replaceable>number</replaceable></optional>
