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$Header: /cvsroot/pgsql/doc/src/sgml/ref/select.sgml,v 1.62 2002/10/18 18:26:22 tgl Exp $
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PostgreSQL documentation
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-->
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<refentry id="SQL-SELECT">
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<refmeta>
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<refentrytitle id="sql-select-title">SELECT</refentrytitle>
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<refmiscinfo>SQL - Language Statements</refmiscinfo>
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</refmeta>
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<refnamediv>
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<refname>
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SELECT
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</refname>
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<refpurpose>
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retrieve rows from a table or view
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</refpurpose></refnamediv>
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<refsynopsisdiv>
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<refsynopsisdivinfo>
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<date>2000-12-11</date>
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</refsynopsisdivinfo>
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<synopsis>
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SELECT [ ALL | DISTINCT [ ON ( <replaceable class="PARAMETER">expression</replaceable> [, ...] ) ] ]
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* | <replaceable class="PARAMETER">expression</replaceable> [ AS <replaceable class="PARAMETER">output_name</replaceable> ] [, ...]
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[ FROM <replaceable class="PARAMETER">from_item</replaceable> [, ...] ]
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[ WHERE <replaceable class="PARAMETER">condition</replaceable> ]
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[ GROUP BY <replaceable class="PARAMETER">expression</replaceable> [, ...] ]
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[ HAVING <replaceable class="PARAMETER">condition</replaceable> [, ...] ]
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[ { UNION | INTERSECT | EXCEPT } [ ALL ] <replaceable class="PARAMETER">select</replaceable> ]
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[ ORDER BY <replaceable class="PARAMETER">expression</replaceable> [ ASC | DESC | USING <replaceable class="PARAMETER">operator</replaceable> ] [, ...] ]
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[ LIMIT { <replaceable class="PARAMETER">count</replaceable> | ALL } ]
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[ OFFSET <replaceable class="PARAMETER">start</replaceable> ]
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[ FOR UPDATE [ OF <replaceable class="PARAMETER">tablename</replaceable> [, ...] ] ]
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where <replaceable class="PARAMETER">from_item</replaceable> can be:
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[ ONLY ] <replaceable class="PARAMETER">table_name</replaceable> [ * ]
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[ [ AS ] <replaceable class="PARAMETER">alias</replaceable> [ ( <replaceable class="PARAMETER">column_alias_list</replaceable> ) ] ]
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( <replaceable class="PARAMETER">select</replaceable> )
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[ AS ] <replaceable class="PARAMETER">alias</replaceable> [ ( <replaceable class="PARAMETER">column_alias_list</replaceable> ) ]
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<replaceable class="PARAMETER">table_function_name</replaceable> ( [ <replaceable class="parameter">argument</replaceable> [, ...] ] )
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Attached are two patches to implement and document anonymous composite
types for Table Functions, as previously proposed on HACKERS. Here is a
brief explanation:
1. Creates a new pg_type typtype: 'p' for pseudo type (currently either
'b' for base or 'c' for catalog, i.e. a class).
2. Creates new builtin type of typtype='p' named RECORD. This is the
first of potentially several pseudo types.
3. Modify FROM clause grammer to accept:
SELECT * FROM my_func() AS m(colname1 type1, colname2 type1, ...)
where m is the table alias, colname1, etc are the column names, and
type1, etc are the column types.
4. When typtype == 'p' and the function return type is RECORD, a list
of column defs is required, and when typtype != 'p', it is
disallowed.
5. A check was added to ensure that the tupdesc provide via the parser
and the actual return tupdesc match in number and type of
attributes.
When creating a function you can do:
CREATE FUNCTION foo(text) RETURNS setof RECORD ...
When using it you can do:
SELECT * from foo(sqlstmt) AS (f1 int, f2 text, f3 timestamp)
or
SELECT * from foo(sqlstmt) AS f(f1 int, f2 text, f3 timestamp)
or
SELECT * from foo(sqlstmt) f(f1 int, f2 text, f3 timestamp)
Included in the patches are adjustments to the regression test sql and
expected files, and documentation.
p.s.
This potentially solves (or at least improves) the issue of builtin
Table Functions. They can be bootstrapped as returning RECORD, and
we can wrap system views around them with properly specified column
defs. For example:
CREATE VIEW pg_settings AS
SELECT s.name, s.setting
FROM show_all_settings()AS s(name text, setting text);
Then we can also add the UPDATE RULE that I previously posted to
pg_settings, and have pg_settings act like a virtual table, allowing
settings to be queried and set.
Joe Conway
23 years ago
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[ AS ] <replaceable class="PARAMETER">alias</replaceable> [ ( <replaceable class="PARAMETER">column_alias_list</replaceable> | <replaceable class="PARAMETER">column_definition_list</replaceable> ) ]
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<replaceable class="PARAMETER">table_function_name</replaceable> ( [ <replaceable class="parameter">argument</replaceable> [, ...] ] )
|
Attached are two patches to implement and document anonymous composite
types for Table Functions, as previously proposed on HACKERS. Here is a
brief explanation:
1. Creates a new pg_type typtype: 'p' for pseudo type (currently either
'b' for base or 'c' for catalog, i.e. a class).
2. Creates new builtin type of typtype='p' named RECORD. This is the
first of potentially several pseudo types.
3. Modify FROM clause grammer to accept:
SELECT * FROM my_func() AS m(colname1 type1, colname2 type1, ...)
where m is the table alias, colname1, etc are the column names, and
type1, etc are the column types.
4. When typtype == 'p' and the function return type is RECORD, a list
of column defs is required, and when typtype != 'p', it is
disallowed.
5. A check was added to ensure that the tupdesc provide via the parser
and the actual return tupdesc match in number and type of
attributes.
When creating a function you can do:
CREATE FUNCTION foo(text) RETURNS setof RECORD ...
When using it you can do:
SELECT * from foo(sqlstmt) AS (f1 int, f2 text, f3 timestamp)
or
SELECT * from foo(sqlstmt) AS f(f1 int, f2 text, f3 timestamp)
or
SELECT * from foo(sqlstmt) f(f1 int, f2 text, f3 timestamp)
Included in the patches are adjustments to the regression test sql and
expected files, and documentation.
p.s.
This potentially solves (or at least improves) the issue of builtin
Table Functions. They can be bootstrapped as returning RECORD, and
we can wrap system views around them with properly specified column
defs. For example:
CREATE VIEW pg_settings AS
SELECT s.name, s.setting
FROM show_all_settings()AS s(name text, setting text);
Then we can also add the UPDATE RULE that I previously posted to
pg_settings, and have pg_settings act like a virtual table, allowing
settings to be queried and set.
Joe Conway
23 years ago
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AS ( <replaceable class="PARAMETER">column_definition_list</replaceable> )
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<replaceable class="PARAMETER">from_item</replaceable> [ NATURAL ] <replaceable class="PARAMETER">join_type</replaceable> <replaceable class="PARAMETER">from_item</replaceable>
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[ ON <replaceable class="PARAMETER">join_condition</replaceable> | USING ( <replaceable class="PARAMETER">join_column_list</replaceable> ) ]
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</synopsis>
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<refsect2 id="R2-SQL-SELECT-1">
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<refsect2info>
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<date>2000-12-11</date>
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</refsect2info>
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<title>
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Inputs
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</title>
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<para>
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<variablelist>
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<varlistentry>
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<term><replaceable class="PARAMETER">expression</replaceable></term>
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<listitem>
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<para>
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The name of a table's column or an expression.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="PARAMETER">output_name</replaceable></term>
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<listitem>
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<para>
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Specifies another name for an output column using
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the AS clause. This name is primarily used to label the column
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for display. It can also be used to refer to the column's value in
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ORDER BY and GROUP BY clauses. But the
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<replaceable class="PARAMETER">output_name</replaceable>
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cannot be used in the WHERE or HAVING clauses; write out the
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expression instead.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="PARAMETER">from_item</replaceable></term>
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<listitem>
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<para>
|
Attached are two patches to implement and document anonymous composite
types for Table Functions, as previously proposed on HACKERS. Here is a
brief explanation:
1. Creates a new pg_type typtype: 'p' for pseudo type (currently either
'b' for base or 'c' for catalog, i.e. a class).
2. Creates new builtin type of typtype='p' named RECORD. This is the
first of potentially several pseudo types.
3. Modify FROM clause grammer to accept:
SELECT * FROM my_func() AS m(colname1 type1, colname2 type1, ...)
where m is the table alias, colname1, etc are the column names, and
type1, etc are the column types.
4. When typtype == 'p' and the function return type is RECORD, a list
of column defs is required, and when typtype != 'p', it is
disallowed.
5. A check was added to ensure that the tupdesc provide via the parser
and the actual return tupdesc match in number and type of
attributes.
When creating a function you can do:
CREATE FUNCTION foo(text) RETURNS setof RECORD ...
When using it you can do:
SELECT * from foo(sqlstmt) AS (f1 int, f2 text, f3 timestamp)
or
SELECT * from foo(sqlstmt) AS f(f1 int, f2 text, f3 timestamp)
or
SELECT * from foo(sqlstmt) f(f1 int, f2 text, f3 timestamp)
Included in the patches are adjustments to the regression test sql and
expected files, and documentation.
p.s.
This potentially solves (or at least improves) the issue of builtin
Table Functions. They can be bootstrapped as returning RECORD, and
we can wrap system views around them with properly specified column
defs. For example:
CREATE VIEW pg_settings AS
SELECT s.name, s.setting
FROM show_all_settings()AS s(name text, setting text);
Then we can also add the UPDATE RULE that I previously posted to
pg_settings, and have pg_settings act like a virtual table, allowing
settings to be queried and set.
Joe Conway
23 years ago
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A table reference, sub-SELECT, table function, or JOIN clause. See below for details.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="PARAMETER">condition</replaceable></term>
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<listitem>
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<para>
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A Boolean expression giving a result of true or false.
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See the WHERE and HAVING clause descriptions below.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="PARAMETER">select</replaceable></term>
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<listitem>
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<para>
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A select statement with all features except the ORDER BY,
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LIMIT/OFFSET, and FOR UPDATE clauses (even those can be used when the
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select is parenthesized).
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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<para>
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FROM items can contain:
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<variablelist>
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<varlistentry>
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<term><replaceable class="PARAMETER">table_name</replaceable></term>
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<listitem>
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<para>
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The name (optionally schema-qualified) of an existing table or view.
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If <literal>ONLY</> is specified, only that table is scanned. If
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<literal>ONLY</> is not specified, the table and all its descendant
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tables (if any) are scanned. <literal>*</> can be appended to the
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table name to indicate that descendant tables are to be scanned, but
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in the current version, this is the default behavior. (In releases
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before 7.1, <literal>ONLY</> was the default behavior.) The
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default behavior can be modified by changing the
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<option>SQL_INHERITANCE</option> configuration option.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="PARAMETER">alias</replaceable></term>
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<listitem>
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<para>
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A substitute name for the FROM item containing the alias.
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An alias is used for brevity or to eliminate ambiguity for self-joins
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(where the same table is scanned multiple times). When an alias
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is provided, it completely hides the actual name of the table or
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table function; for example given <literal>FROM foo AS f</>, the
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remainder of the SELECT must refer to this FROM item as <literal>f</>
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not <literal>foo</>.
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If an alias is
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written, a column alias list can also be written to provide
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substitute names for one or more columns of the table.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="PARAMETER">select</replaceable></term>
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<listitem>
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<para>
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A sub-SELECT can appear in the FROM clause. This acts as though
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its output were created as a temporary table for the duration of
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this single SELECT command. Note that the sub-SELECT must be
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surrounded by parentheses, and an alias <emphasis>must</emphasis>
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be provided for it.
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</para>
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</listitem>
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</varlistentry>
|
Attached are two patches to implement and document anonymous composite
types for Table Functions, as previously proposed on HACKERS. Here is a
brief explanation:
1. Creates a new pg_type typtype: 'p' for pseudo type (currently either
'b' for base or 'c' for catalog, i.e. a class).
2. Creates new builtin type of typtype='p' named RECORD. This is the
first of potentially several pseudo types.
3. Modify FROM clause grammer to accept:
SELECT * FROM my_func() AS m(colname1 type1, colname2 type1, ...)
where m is the table alias, colname1, etc are the column names, and
type1, etc are the column types.
4. When typtype == 'p' and the function return type is RECORD, a list
of column defs is required, and when typtype != 'p', it is
disallowed.
5. A check was added to ensure that the tupdesc provide via the parser
and the actual return tupdesc match in number and type of
attributes.
When creating a function you can do:
CREATE FUNCTION foo(text) RETURNS setof RECORD ...
When using it you can do:
SELECT * from foo(sqlstmt) AS (f1 int, f2 text, f3 timestamp)
or
SELECT * from foo(sqlstmt) AS f(f1 int, f2 text, f3 timestamp)
or
SELECT * from foo(sqlstmt) f(f1 int, f2 text, f3 timestamp)
Included in the patches are adjustments to the regression test sql and
expected files, and documentation.
p.s.
This potentially solves (or at least improves) the issue of builtin
Table Functions. They can be bootstrapped as returning RECORD, and
we can wrap system views around them with properly specified column
defs. For example:
CREATE VIEW pg_settings AS
SELECT s.name, s.setting
FROM show_all_settings()AS s(name text, setting text);
Then we can also add the UPDATE RULE that I previously posted to
pg_settings, and have pg_settings act like a virtual table, allowing
settings to be queried and set.
Joe Conway
23 years ago
|
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|
|
|
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<varlistentry>
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<term><replaceable class="PARAMETER">table function</replaceable></term>
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<listitem>
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<para>
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A table function can appear in the FROM clause. This acts as though
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its output were created as a temporary table for the duration of
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this single SELECT command. An alias may also be used. If an alias is
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written, a column alias list can also be written to provide substitute
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names for one or more columns of the table function. If the table
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function has been defined as returning the <type>record</> data type,
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an alias, or the keyword <literal>AS</>, must be present, followed by
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a column definition list in the form ( <replaceable
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class="PARAMETER">column_name</replaceable> <replaceable
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class="PARAMETER">data_type</replaceable> [, ... ] ).
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The column definition list must match the actual number and types
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|
|
of columns returned by the function.
|
Attached are two patches to implement and document anonymous composite
types for Table Functions, as previously proposed on HACKERS. Here is a
brief explanation:
1. Creates a new pg_type typtype: 'p' for pseudo type (currently either
'b' for base or 'c' for catalog, i.e. a class).
2. Creates new builtin type of typtype='p' named RECORD. This is the
first of potentially several pseudo types.
3. Modify FROM clause grammer to accept:
SELECT * FROM my_func() AS m(colname1 type1, colname2 type1, ...)
where m is the table alias, colname1, etc are the column names, and
type1, etc are the column types.
4. When typtype == 'p' and the function return type is RECORD, a list
of column defs is required, and when typtype != 'p', it is
disallowed.
5. A check was added to ensure that the tupdesc provide via the parser
and the actual return tupdesc match in number and type of
attributes.
When creating a function you can do:
CREATE FUNCTION foo(text) RETURNS setof RECORD ...
When using it you can do:
SELECT * from foo(sqlstmt) AS (f1 int, f2 text, f3 timestamp)
or
SELECT * from foo(sqlstmt) AS f(f1 int, f2 text, f3 timestamp)
or
SELECT * from foo(sqlstmt) f(f1 int, f2 text, f3 timestamp)
Included in the patches are adjustments to the regression test sql and
expected files, and documentation.
p.s.
This potentially solves (or at least improves) the issue of builtin
Table Functions. They can be bootstrapped as returning RECORD, and
we can wrap system views around them with properly specified column
defs. For example:
CREATE VIEW pg_settings AS
SELECT s.name, s.setting
FROM show_all_settings()AS s(name text, setting text);
Then we can also add the UPDATE RULE that I previously posted to
pg_settings, and have pg_settings act like a virtual table, allowing
settings to be queried and set.
Joe Conway
23 years ago
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|
</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><replaceable class="PARAMETER">join_type</replaceable></term>
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<listitem>
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<para>
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One of
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<command>[ INNER ] JOIN</command>,
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<command>LEFT [ OUTER ] JOIN</command>,
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<command>RIGHT [ OUTER ] JOIN</command>,
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<command>FULL [ OUTER ] JOIN</command>, or
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|
|
|
<command>CROSS JOIN</command>.
|
|
|
|
|
For INNER and OUTER join types, exactly one of NATURAL,
|
|
|
|
|
ON <replaceable class="PARAMETER">join_condition</replaceable>, or
|
|
|
|
|
USING ( <replaceable class="PARAMETER">join_column_list</replaceable> )
|
|
|
|
|
must appear. For CROSS JOIN, none of these items may appear.
|
|
|
|
|
</para>
|
|
|
|
|
</listitem>
|
|
|
|
|
</varlistentry>
|
|
|
|
|
|
|
|
|
|
<varlistentry>
|
|
|
|
|
<term><replaceable class="PARAMETER">join_condition</replaceable></term>
|
|
|
|
|
<listitem>
|
|
|
|
|
<para>
|
|
|
|
|
A qualification condition. This is similar to the WHERE condition
|
|
|
|
|
except that it only applies to the two from_items being joined in
|
|
|
|
|
this JOIN clause.
|
|
|
|
|
</para>
|
|
|
|
|
</listitem>
|
|
|
|
|
</varlistentry>
|
|
|
|
|
|
|
|
|
|
<varlistentry>
|
|
|
|
|
<term><replaceable class="PARAMETER">join_column_list</replaceable></term>
|
|
|
|
|
<listitem>
|
|
|
|
|
<para>
|
|
|
|
|
A USING column list ( a, b, ... ) is shorthand for the ON condition
|
|
|
|
|
left_table.a = right_table.a AND left_table.b = right_table.b ...
|
|
|
|
|
</para>
|
|
|
|
|
</listitem>
|
|
|
|
|
</varlistentry>
|
|
|
|
|
|
|
|
|
|
</variablelist>
|
|
|
|
|
</para>
|
|
|
|
|
</refsect2>
|
|
|
|
|
|
|
|
|
|
<refsect2 id="R2-SQL-SELECT-2">
|
|
|
|
|
<refsect2info>
|
|
|
|
|
<date>1998-09-24</date>
|
|
|
|
|
</refsect2info>
|
|
|
|
|
<title>
|
|
|
|
|
Outputs
|
|
|
|
|
</title>
|
|
|
|
|
<para>
|
|
|
|
|
|
|
|
|
|
<variablelist>
|
|
|
|
|
<varlistentry>
|
|
|
|
|
<term>Rows</term>
|
|
|
|
|
<listitem>
|
|
|
|
|
<para>
|
|
|
|
|
The complete set of rows resulting from the query specification.
|
|
|
|
|
</para>
|
|
|
|
|
</listitem>
|
|
|
|
|
</varlistentry>
|
|
|
|
|
|
|
|
|
|
<varlistentry>
|
|
|
|
|
<term>
|
|
|
|
|
<returnvalue><replaceable>count</replaceable></returnvalue>
|
|
|
|
|
</term>
|
|
|
|
|
<listitem>
|
|
|
|
|
<para>
|
|
|
|
|
The count of rows returned by the query.
|
|
|
|
|
</para>
|
|
|
|
|
</listitem>
|
|
|
|
|
</varlistentry>
|
|
|
|
|
</variablelist>
|
|
|
|
|
</para>
|
|
|
|
|
</refsect2>
|
|
|
|
|
</refsynopsisdiv>
|
|
|
|
|
|
|
|
|
|
<refsect1 id="R1-SQL-SELECT-1">
|
|
|
|
|
<refsect1info>
|
|
|
|
|
<date>2000-12-11</date>
|
|
|
|
|
</refsect1info>
|
|
|
|
|
<title>
|
|
|
|
|
Description
|
|
|
|
|
</title>
|
|
|
|
|
<para>
|
|
|
|
|
<command>SELECT</command> will return rows from one or more tables.
|
|
|
|
|
Candidates for selection are rows which satisfy the WHERE condition;
|
|
|
|
|
if WHERE is omitted, all rows are candidates.
|
|
|
|
|
(See <xref linkend="sql-where" endterm="sql-where-title">.)
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
Actually, the returned rows are not directly the rows produced by the
|
|
|
|
|
FROM/WHERE/GROUP BY/HAVING clauses; rather, the output rows are formed
|
|
|
|
|
by computing the SELECT output expressions for each selected row.
|
|
|
|
|
<command>*</command> can be written in the output list as a shorthand
|
|
|
|
|
for all the columns of the selected rows. Also, one can write
|
|
|
|
|
<replaceable class="PARAMETER">table_name</replaceable><command>.*</command>
|
|
|
|
|
as a shorthand for the columns coming from just that table.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
<command>DISTINCT</command> will eliminate duplicate rows from the
|
|
|
|
|
result.
|
|
|
|
|
<command>ALL</command> (the default) will return all candidate rows,
|
|
|
|
|
including duplicates.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
<command>DISTINCT ON</command> eliminates rows that match on all the
|
|
|
|
|
specified expressions, keeping only the first row of each set of
|
|
|
|
|
duplicates. The DISTINCT ON expressions are interpreted using the
|
|
|
|
|
same rules as for ORDER BY items; see below.
|
|
|
|
|
Note that the <quote>first row</quote> of each set is unpredictable
|
|
|
|
|
unless <command>ORDER BY</command> is used to ensure that the desired
|
|
|
|
|
row appears first. For example,
|
|
|
|
|
<programlisting>
|
|
|
|
|
SELECT DISTINCT ON (location) location, time, report
|
|
|
|
|
FROM weatherReports
|
|
|
|
|
ORDER BY location, time DESC;
|
|
|
|
|
</programlisting>
|
|
|
|
|
retrieves the most recent weather report for each location. But if
|
|
|
|
|
we had not used ORDER BY to force descending order of time values
|
|
|
|
|
for each location, we'd have gotten a report of unpredictable age
|
|
|
|
|
for each location.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
The GROUP BY clause allows a user to divide a table
|
|
|
|
|
into groups of rows that match on one or more values.
|
|
|
|
|
(See <xref linkend="sql-groupby" endterm="sql-groupby-title">.)
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
The HAVING clause allows selection of only those groups of rows
|
|
|
|
|
meeting the specified condition.
|
|
|
|
|
(See <xref linkend="sql-having" endterm="sql-having-title">.)
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
The ORDER BY clause causes the returned rows to be sorted in a specified
|
|
|
|
|
order. If ORDER BY is not given, the rows are returned in whatever order
|
|
|
|
|
the system finds cheapest to produce.
|
|
|
|
|
(See <xref linkend="sql-orderby" endterm="sql-orderby-title">.)
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
SELECT queries can be combined using UNION, INTERSECT, and EXCEPT
|
|
|
|
|
operators. Use parentheses if necessary to determine the ordering
|
|
|
|
|
of these operators.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
The UNION operator computes the collection of rows
|
|
|
|
|
returned by the queries involved.
|
|
|
|
|
Duplicate rows are eliminated unless ALL is specified.
|
|
|
|
|
(See <xref linkend="sql-union" endterm="sql-union-title">.)
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
The INTERSECT operator computes the rows that are common to both queries.
|
|
|
|
|
Duplicate rows are eliminated unless ALL is specified.
|
|
|
|
|
(See <xref linkend="sql-intersect" endterm="sql-intersect-title">.)
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
The EXCEPT operator computes the rows returned by the first query but
|
|
|
|
|
not the second query.
|
|
|
|
|
Duplicate rows are eliminated unless ALL is specified.
|
|
|
|
|
(See <xref linkend="sql-except" endterm="sql-except-title">.)
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
The LIMIT clause allows a subset of the rows produced by the query
|
|
|
|
|
to be returned to the user.
|
|
|
|
|
(See <xref linkend="sql-limit" endterm="sql-limit-title">.)
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
The FOR UPDATE clause causes the SELECT statement to lock the selected
|
|
|
|
|
rows against concurrent updates.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
You must have SELECT privilege to a table to read its values
|
|
|
|
|
(See the <command>GRANT</command>/<command>REVOKE</command> statements).
|
|
|
|
|
Use of FOR UPDATE requires UPDATE privilege as well.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<refsect2 id="SQL-FROM">
|
|
|
|
|
<refsect2info>
|
|
|
|
|
<date>2000-12-11</date>
|
|
|
|
|
</refsect2info>
|
|
|
|
|
<title id="sql-from-title">
|
|
|
|
|
FROM Clause
|
|
|
|
|
</title>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
The FROM clause specifies one or more source tables for the SELECT.
|
|
|
|
|
If multiple sources are specified, the result is conceptually the
|
|
|
|
|
Cartesian product of all the rows in all the sources --- but usually
|
|
|
|
|
qualification conditions are added to restrict the returned rows to
|
|
|
|
|
a small subset of the Cartesian product.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
When a FROM item is a simple table name, it implicitly includes rows
|
|
|
|
|
from sub-tables (inheritance children) of the table.
|
|
|
|
|
<command>ONLY</command> will
|
|
|
|
|
suppress rows from sub-tables of the table. Before
|
|
|
|
|
<Productname>PostgreSQL</Productname> 7.1,
|
|
|
|
|
this was the default result, and adding sub-tables was done
|
|
|
|
|
by appending <command>*</command> to the table name.
|
|
|
|
|
This old behavior is available via the command
|
|
|
|
|
<command>SET SQL_Inheritance TO OFF</command>.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
A FROM item can also be a parenthesized sub-SELECT (note that an
|
|
|
|
|
alias clause is required for a sub-SELECT!). This is an extremely
|
|
|
|
|
handy feature since it's the only way to get multiple levels of
|
|
|
|
|
grouping, aggregation, or sorting in a single query.
|
|
|
|
|
</para>
|
|
|
|
|
|
Attached are two patches to implement and document anonymous composite
types for Table Functions, as previously proposed on HACKERS. Here is a
brief explanation:
1. Creates a new pg_type typtype: 'p' for pseudo type (currently either
'b' for base or 'c' for catalog, i.e. a class).
2. Creates new builtin type of typtype='p' named RECORD. This is the
first of potentially several pseudo types.
3. Modify FROM clause grammer to accept:
SELECT * FROM my_func() AS m(colname1 type1, colname2 type1, ...)
where m is the table alias, colname1, etc are the column names, and
type1, etc are the column types.
4. When typtype == 'p' and the function return type is RECORD, a list
of column defs is required, and when typtype != 'p', it is
disallowed.
5. A check was added to ensure that the tupdesc provide via the parser
and the actual return tupdesc match in number and type of
attributes.
When creating a function you can do:
CREATE FUNCTION foo(text) RETURNS setof RECORD ...
When using it you can do:
SELECT * from foo(sqlstmt) AS (f1 int, f2 text, f3 timestamp)
or
SELECT * from foo(sqlstmt) AS f(f1 int, f2 text, f3 timestamp)
or
SELECT * from foo(sqlstmt) f(f1 int, f2 text, f3 timestamp)
Included in the patches are adjustments to the regression test sql and
expected files, and documentation.
p.s.
This potentially solves (or at least improves) the issue of builtin
Table Functions. They can be bootstrapped as returning RECORD, and
we can wrap system views around them with properly specified column
defs. For example:
CREATE VIEW pg_settings AS
SELECT s.name, s.setting
FROM show_all_settings()AS s(name text, setting text);
Then we can also add the UPDATE RULE that I previously posted to
pg_settings, and have pg_settings act like a virtual table, allowing
settings to be queried and set.
Joe Conway
23 years ago
|
|
|
<para>
|
|
|
|
|
A FROM item can be a table function (typically, a function that returns
|
|
|
|
|
multiple rows and/or columns, though actually any function can be used).
|
|
|
|
|
The function is invoked with the given argument value(s), and then its
|
|
|
|
|
output is scanned as though it were a table.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
In some cases it is useful to define table functions that can return
|
|
|
|
|
different column sets depending on how they are invoked. To support this,
|
|
|
|
|
the table function can be declared as returning the pseudo-type
|
|
|
|
|
<type>record</>. When such a function is used in FROM, it must be
|
|
|
|
|
followed by an alias, or the keyword <literal>AS</> alone,
|
|
|
|
|
and then by a parenthesized list of column names and types. This provides
|
|
|
|
|
a query-time composite type definition. The composite type definition
|
|
|
|
|
must match the actual composite type returned from the function, or an
|
|
|
|
|
error will be reported at run-time.
|
Attached are two patches to implement and document anonymous composite
types for Table Functions, as previously proposed on HACKERS. Here is a
brief explanation:
1. Creates a new pg_type typtype: 'p' for pseudo type (currently either
'b' for base or 'c' for catalog, i.e. a class).
2. Creates new builtin type of typtype='p' named RECORD. This is the
first of potentially several pseudo types.
3. Modify FROM clause grammer to accept:
SELECT * FROM my_func() AS m(colname1 type1, colname2 type1, ...)
where m is the table alias, colname1, etc are the column names, and
type1, etc are the column types.
4. When typtype == 'p' and the function return type is RECORD, a list
of column defs is required, and when typtype != 'p', it is
disallowed.
5. A check was added to ensure that the tupdesc provide via the parser
and the actual return tupdesc match in number and type of
attributes.
When creating a function you can do:
CREATE FUNCTION foo(text) RETURNS setof RECORD ...
When using it you can do:
SELECT * from foo(sqlstmt) AS (f1 int, f2 text, f3 timestamp)
or
SELECT * from foo(sqlstmt) AS f(f1 int, f2 text, f3 timestamp)
or
SELECT * from foo(sqlstmt) f(f1 int, f2 text, f3 timestamp)
Included in the patches are adjustments to the regression test sql and
expected files, and documentation.
p.s.
This potentially solves (or at least improves) the issue of builtin
Table Functions. They can be bootstrapped as returning RECORD, and
we can wrap system views around them with properly specified column
defs. For example:
CREATE VIEW pg_settings AS
SELECT s.name, s.setting
FROM show_all_settings()AS s(name text, setting text);
Then we can also add the UPDATE RULE that I previously posted to
pg_settings, and have pg_settings act like a virtual table, allowing
settings to be queried and set.
Joe Conway
23 years ago
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
Finally, a FROM item can be a JOIN clause, which combines two simpler
|
|
|
|
|
FROM items. (Use parentheses if necessary to determine the order
|
|
|
|
|
of nesting.)
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
A CROSS JOIN or INNER JOIN is a simple Cartesian product,
|
|
|
|
|
the same as you get from listing the two items at the top level of FROM.
|
|
|
|
|
CROSS JOIN is equivalent to INNER JOIN ON (TRUE), that is, no rows are
|
|
|
|
|
removed by qualification. These join types are just a notational
|
|
|
|
|
convenience, since they do nothing you couldn't do with plain FROM and
|
|
|
|
|
WHERE.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
LEFT OUTER JOIN returns all rows in the qualified Cartesian product
|
|
|
|
|
(i.e., all combined rows that pass its ON condition), plus one copy of each
|
|
|
|
|
row in the left-hand table for which there was no right-hand row that
|
|
|
|
|
passed the ON condition. This left-hand row is extended to the full
|
|
|
|
|
width of the joined table by inserting null values for the right-hand columns.
|
|
|
|
|
Note that only the <literal>JOIN</>'s own ON or USING condition is considered while
|
|
|
|
|
deciding which rows have matches. Outer ON or WHERE conditions are
|
|
|
|
|
applied afterwards.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
Conversely, RIGHT OUTER JOIN returns all the joined rows, plus one row
|
|
|
|
|
for each unmatched right-hand row (extended with nulls on the left).
|
|
|
|
|
This is just a notational
|
|
|
|
|
convenience, since you could convert it to a LEFT OUTER JOIN by switching
|
|
|
|
|
the left and right inputs.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
FULL OUTER JOIN returns all the joined rows, plus one row for each
|
|
|
|
|
unmatched left-hand row (extended with nulls on the right), plus one row
|
|
|
|
|
for each unmatched right-hand row (extended with nulls on the left).
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
For all the JOIN types except CROSS JOIN, you must write exactly one of
|
|
|
|
|
ON <replaceable class="PARAMETER">join_condition</replaceable>,
|
|
|
|
|
USING ( <replaceable class="PARAMETER">join_column_list</replaceable> ),
|
|
|
|
|
or NATURAL. ON is the most general case: you can write any qualification
|
|
|
|
|
expression involving the two tables to be joined.
|
|
|
|
|
A USING column list ( a, b, ... ) is shorthand for the ON condition
|
|
|
|
|
left_table.a = right_table.a AND left_table.b = right_table.b ...
|
|
|
|
|
Also, USING implies that only one of each pair of equivalent columns will
|
|
|
|
|
be included in the JOIN output, not both. NATURAL is shorthand for
|
|
|
|
|
a USING list that mentions all similarly-named columns in the tables.
|
|
|
|
|
</para>
|
|
|
|
|
</refsect2>
|
|
|
|
|
|
|
|
|
|
<refsect2 id="SQL-WHERE">
|
|
|
|
|
<refsect2info>
|
|
|
|
|
<date>2000-03-15</date>
|
|
|
|
|
</refsect2info>
|
|
|
|
|
<title id="sql-where-title">
|
|
|
|
|
WHERE Clause
|
|
|
|
|
</title>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
The optional WHERE condition has the general form:
|
|
|
|
|
|
|
|
|
|
<synopsis>
|
|
|
|
|
WHERE <replaceable class="PARAMETER">boolean_expr</replaceable>
|
|
|
|
|
</synopsis>
|
|
|
|
|
|
|
|
|
|
<replaceable class="PARAMETER">boolean_expr</replaceable>
|
|
|
|
|
can consist of any expression which evaluates to a Boolean value.
|
|
|
|
|
In many cases, this expression will be:
|
|
|
|
|
|
|
|
|
|
<synopsis>
|
|
|
|
|
<replaceable class="PARAMETER">expr</replaceable> <replaceable class="PARAMETER">cond_op</replaceable> <replaceable class="PARAMETER">expr</replaceable>
|
|
|
|
|
</synopsis>
|
|
|
|
|
|
|
|
|
|
or
|
|
|
|
|
|
|
|
|
|
<synopsis>
|
|
|
|
|
<replaceable class="PARAMETER">log_op</replaceable> <replaceable class="PARAMETER">expr</replaceable>
|
|
|
|
|
</synopsis>
|
|
|
|
|
|
|
|
|
|
where <replaceable class="PARAMETER">cond_op</replaceable>
|
|
|
|
|
can be one of: =, <, <=, >, >= or <>,
|
|
|
|
|
a conditional operator like ALL, ANY, IN, LIKE, or a
|
|
|
|
|
locally defined operator,
|
|
|
|
|
and <replaceable class="PARAMETER">log_op</replaceable> can be one
|
|
|
|
|
of: AND, OR, NOT.
|
|
|
|
|
SELECT will ignore all rows for which the WHERE condition does not return
|
|
|
|
|
TRUE.
|
|
|
|
|
</para>
|
|
|
|
|
</refsect2>
|
|
|
|
|
|
|
|
|
|
<refsect2 id="SQL-GROUPBY">
|
|
|
|
|
<refsect2info>
|
|
|
|
|
<date>2000-03-15</date>
|
|
|
|
|
</refsect2info>
|
|
|
|
|
<title id="sql-groupby-title">
|
|
|
|
|
GROUP BY Clause
|
|
|
|
|
</title>
|
|
|
|
|
<para>
|
|
|
|
|
GROUP BY specifies a grouped table derived by the application
|
|
|
|
|
of this clause:
|
|
|
|
|
<synopsis>
|
|
|
|
|
GROUP BY <replaceable class="PARAMETER">expression</replaceable> [, ...]
|
|
|
|
|
</synopsis>
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
GROUP BY will condense into a single row all selected rows that share the
|
|
|
|
|
same values for the grouped columns. Aggregate functions, if any,
|
|
|
|
|
are computed across all rows making up each group, producing a
|
|
|
|
|
separate value for each group (whereas without GROUP BY, an
|
|
|
|
|
aggregate produces a single value computed across all the selected
|
|
|
|
|
rows). When GROUP BY is present, it is not valid for the SELECT
|
|
|
|
|
output expression(s) to refer to
|
|
|
|
|
ungrouped columns except within aggregate functions, since there
|
|
|
|
|
would be more than one possible value to return for an ungrouped column.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
A GROUP BY item can be an input column name, or the name or ordinal
|
|
|
|
|
number of an output column (SELECT expression), or it can be an arbitrary
|
|
|
|
|
expression formed from input-column values. In case of ambiguity, a GROUP
|
|
|
|
|
BY name will
|
|
|
|
|
be interpreted as an input-column name rather than an output column name.
|
|
|
|
|
</para>
|
|
|
|
|
</refsect2>
|
|
|
|
|
|
|
|
|
|
<refsect2 id="SQL-HAVING">
|
|
|
|
|
<refsect2info>
|
|
|
|
|
<date>2000-03-15</date>
|
|
|
|
|
</refsect2info>
|
|
|
|
|
<title id="sql-having-title">
|
|
|
|
|
HAVING Clause
|
|
|
|
|
</title>
|
|
|
|
|
<para>
|
|
|
|
|
The optional HAVING condition has the general form:
|
|
|
|
|
|
|
|
|
|
<synopsis>
|
|
|
|
|
HAVING <replaceable class="PARAMETER">boolean_expr</replaceable>
|
|
|
|
|
</synopsis>
|
|
|
|
|
|
|
|
|
|
where <replaceable class="PARAMETER">boolean_expr</replaceable> is the same
|
|
|
|
|
as specified for the WHERE clause.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
HAVING specifies a grouped table derived by the elimination
|
|
|
|
|
of group rows that do not satisfy the
|
|
|
|
|
<replaceable class="PARAMETER">boolean_expr</replaceable>.
|
|
|
|
|
HAVING is different from WHERE:
|
|
|
|
|
WHERE filters individual rows before application of GROUP BY,
|
|
|
|
|
while HAVING filters group rows created by GROUP BY.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
Each column referenced in
|
|
|
|
|
<replaceable class="PARAMETER">boolean_expr</replaceable> shall unambiguously
|
|
|
|
|
reference a grouping column, unless the reference appears within an
|
|
|
|
|
aggregate function.
|
|
|
|
|
</para>
|
|
|
|
|
</refsect2>
|
|
|
|
|
|
|
|
|
|
<refsect2 id="SQL-ORDERBY">
|
|
|
|
|
<refsect2info>
|
|
|
|
|
<date>2000-03-15</date>
|
|
|
|
|
</refsect2info>
|
|
|
|
|
<title id="sql-orderby-title">
|
|
|
|
|
ORDER BY Clause
|
|
|
|
|
</title>
|
|
|
|
|
<para>
|
|
|
|
|
<synopsis>
|
|
|
|
|
ORDER BY <replaceable class="PARAMETER">expression</replaceable> [ ASC | DESC | USING <replaceable class="PARAMETER">operator</replaceable> ] [, ...]
|
|
|
|
|
</synopsis></para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
An ORDER BY item can be the name or ordinal
|
|
|
|
|
number of an output column (SELECT expression), or it can be an arbitrary
|
|
|
|
|
expression formed from input-column values. In case of ambiguity, an
|
|
|
|
|
ORDER BY name will be interpreted as an output-column name.
|
|
|
|
|
</para>
|
|
|
|
|
<para>
|
|
|
|
|
The ordinal number refers to the ordinal (left-to-right) position
|
|
|
|
|
of the result column. This feature makes it possible to define an ordering
|
|
|
|
|
on the basis of a column that does not have a proper name.
|
|
|
|
|
This is never absolutely necessary because it is always possible
|
|
|
|
|
to assign a name to a result column using the AS clause, e.g.:
|
|
|
|
|
<programlisting>
|
|
|
|
|
SELECT title, date_prod + 1 AS newlen FROM films ORDER BY newlen;
|
|
|
|
|
</programlisting></para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
It is also possible to ORDER BY
|
|
|
|
|
arbitrary expressions (an extension to SQL92),
|
|
|
|
|
including fields that do not appear in the
|
|
|
|
|
SELECT result list.
|
|
|
|
|
Thus the following statement is legal:
|
|
|
|
|
<programlisting>
|
|
|
|
|
SELECT name FROM distributors ORDER BY code;
|
|
|
|
|
</programlisting>
|
|
|
|
|
A limitation of this feature is that an ORDER BY clause applying to the
|
|
|
|
|
result of a UNION, INTERSECT, or EXCEPT query may only specify an output
|
|
|
|
|
column name or number, not an expression.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
Note that if an ORDER BY item is a simple name that matches both
|
|
|
|
|
a result column name and an input column name, ORDER BY will interpret
|
|
|
|
|
it as the result column name. This is the opposite of the choice that
|
|
|
|
|
GROUP BY will make in the same situation. This inconsistency is
|
|
|
|
|
mandated by the SQL92 standard.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
Optionally one may add the key word <literal>DESC</> (descending)
|
|
|
|
|
or <literal>ASC</> (ascending) after each column name in the
|
|
|
|
|
<literal>ORDER BY</> clause. If not specified, <literal>ASC</> is
|
|
|
|
|
assumed by default. Alternatively, a specific ordering operator
|
|
|
|
|
name may be specified. <literal>ASC</> is equivalent to
|
|
|
|
|
<literal>USING <</> and <literal>DESC</> is equivalent to
|
|
|
|
|
<literal>USING ></>.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
The null value sorts higher than any other value in a domain. In other
|
|
|
|
|
words, with ascending sort order nulls sort at the end and with
|
|
|
|
|
descending sort order nulls sort at the beginning.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
</refsect2>
|
|
|
|
|
|
|
|
|
|
<refsect2 id="SQL-UNION">
|
|
|
|
|
<refsect2info>
|
|
|
|
|
<date>2000-12-11</date>
|
|
|
|
|
</refsect2info>
|
|
|
|
|
<title id="sql-union-title">
|
|
|
|
|
UNION Clause
|
|
|
|
|
</title>
|
|
|
|
|
<para>
|
|
|
|
|
<synopsis>
|
|
|
|
|
<replaceable class="PARAMETER">table_query</replaceable> UNION [ ALL ] <replaceable class="PARAMETER">table_query</replaceable>
|
|
|
|
|
[ ORDER BY <replaceable class="PARAMETER">expression</replaceable> [ ASC | DESC | USING <replaceable class="PARAMETER">operator</replaceable> ] [, ...] ]
|
|
|
|
|
[ LIMIT { <replaceable class="PARAMETER">count</replaceable> | ALL } ]
|
|
|
|
|
[ OFFSET <replaceable class="PARAMETER">start</replaceable> ]
|
|
|
|
|
</synopsis>
|
|
|
|
|
|
|
|
|
|
where
|
|
|
|
|
<replaceable class="PARAMETER">table_query</replaceable>
|
|
|
|
|
specifies any select expression without an ORDER BY, LIMIT, or FOR UPDATE
|
|
|
|
|
clause. (ORDER BY and LIMIT can be attached to a sub-expression
|
|
|
|
|
if it is enclosed in parentheses. Without parentheses, these clauses
|
|
|
|
|
will be taken to apply to the result of the UNION, not to its right-hand
|
|
|
|
|
input expression.)
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
The UNION operator computes the collection (set union) of the rows
|
|
|
|
|
returned by the queries involved.
|
|
|
|
|
The two SELECT statements that represent the direct operands of the UNION must
|
|
|
|
|
produce the same number of columns, and corresponding columns must be
|
|
|
|
|
of compatible data types.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
The result of UNION does not contain any duplicate rows
|
|
|
|
|
unless the ALL option is specified. ALL prevents elimination of
|
|
|
|
|
duplicates.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
Multiple UNION operators in the same SELECT statement are
|
|
|
|
|
evaluated left to right, unless otherwise indicated by parentheses.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
Currently, FOR UPDATE may not be specified either for a UNION result
|
|
|
|
|
or for the inputs of a UNION.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
</refsect2>
|
|
|
|
|
|
|
|
|
|
<refsect2 id="SQL-INTERSECT">
|
|
|
|
|
<refsect2info>
|
|
|
|
|
<date>2000-12-11</date>
|
|
|
|
|
</refsect2info>
|
|
|
|
|
<title id="sql-intersect-title">
|
|
|
|
|
INTERSECT Clause
|
|
|
|
|
</title>
|
|
|
|
|
<para>
|
|
|
|
|
<synopsis>
|
|
|
|
|
<replaceable class="PARAMETER">table_query</replaceable> INTERSECT [ ALL ] <replaceable class="PARAMETER">table_query</replaceable>
|
|
|
|
|
[ ORDER BY <replaceable class="PARAMETER">expression</replaceable> [ ASC | DESC | USING <replaceable class="PARAMETER">operator</replaceable> ] [, ...] ]
|
|
|
|
|
[ LIMIT { <replaceable class="PARAMETER">count</replaceable> | ALL } ]
|
|
|
|
|
[ OFFSET <replaceable class="PARAMETER">start</replaceable> ]
|
|
|
|
|
</synopsis>
|
|
|
|
|
|
|
|
|
|
where
|
|
|
|
|
<replaceable class="PARAMETER">table_query</replaceable>
|
|
|
|
|
specifies any select expression without an ORDER BY, LIMIT, or
|
|
|
|
|
FOR UPDATE clause.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
INTERSECT is similar to UNION, except that it produces only rows that
|
|
|
|
|
appear in both query outputs, rather than rows that appear in either.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
The result of INTERSECT does not contain any duplicate rows
|
|
|
|
|
unless the ALL option is specified. With ALL, a row that has
|
|
|
|
|
m duplicates in L and n duplicates in R will appear min(m,n) times.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
Multiple INTERSECT operators in the same SELECT statement are
|
|
|
|
|
evaluated left to right, unless parentheses dictate otherwise.
|
|
|
|
|
INTERSECT binds more tightly than UNION --- that is,
|
|
|
|
|
A UNION B INTERSECT C will be read as
|
|
|
|
|
A UNION (B INTERSECT C) unless otherwise specified by parentheses.
|
|
|
|
|
</para>
|
|
|
|
|
</refsect2>
|
|
|
|
|
|
|
|
|
|
<refsect2 id="SQL-EXCEPT">
|
|
|
|
|
<refsect2info>
|
|
|
|
|
<date>2000-12-11</date>
|
|
|
|
|
</refsect2info>
|
|
|
|
|
<title id="sql-except-title">
|
|
|
|
|
EXCEPT Clause
|
|
|
|
|
</title>
|
|
|
|
|
<para>
|
|
|
|
|
<synopsis>
|
|
|
|
|
<replaceable class="PARAMETER">table_query</replaceable> EXCEPT [ ALL ] <replaceable class="PARAMETER">table_query</replaceable>
|
|
|
|
|
[ ORDER BY <replaceable class="PARAMETER">expression</replaceable> [ ASC | DESC | USING <replaceable class="PARAMETER">operator</replaceable> ] [, ...] ]
|
|
|
|
|
[ LIMIT { <replaceable class="PARAMETER">count</replaceable> | ALL } ]
|
|
|
|
|
[ OFFSET <replaceable class="PARAMETER">start</replaceable> ]
|
|
|
|
|
</synopsis>
|
|
|
|
|
|
|
|
|
|
where
|
|
|
|
|
<replaceable class="PARAMETER">table_query</replaceable>
|
|
|
|
|
specifies any select expression without an ORDER BY, LIMIT,
|
|
|
|
|
or FOR UPDATE clause.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
EXCEPT is similar to UNION, except that it produces only rows that
|
|
|
|
|
appear in the left query's output but not in the right query's output.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
The result of EXCEPT does not contain any duplicate rows
|
|
|
|
|
unless the ALL option is specified. With ALL, a row that has
|
|
|
|
|
m duplicates in L and n duplicates in R will appear max(m-n,0) times.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
Multiple EXCEPT operators in the same SELECT statement are
|
|
|
|
|
evaluated left to right, unless parentheses dictate otherwise.
|
|
|
|
|
EXCEPT binds at the same level as UNION.
|
|
|
|
|
</para>
|
|
|
|
|
</refsect2>
|
|
|
|
|
|
|
|
|
|
<refsect2 id="SQL-LIMIT">
|
|
|
|
|
<refsect2info>
|
|
|
|
|
<date>2000-02-20</date>
|
|
|
|
|
</refsect2info>
|
|
|
|
|
<title id="sql-limit-title">
|
|
|
|
|
LIMIT Clause
|
|
|
|
|
</title>
|
|
|
|
|
<para>
|
|
|
|
|
<synopsis>
|
|
|
|
|
LIMIT { <replaceable class="PARAMETER">count</replaceable> | ALL }
|
|
|
|
|
OFFSET <replaceable class="PARAMETER">start</replaceable>
|
|
|
|
|
</synopsis>
|
|
|
|
|
|
|
|
|
|
where
|
|
|
|
|
<replaceable class="PARAMETER">count</replaceable> specifies the
|
|
|
|
|
maximum number of rows to return, and
|
|
|
|
|
<replaceable class="PARAMETER">start</replaceable> specifies the
|
|
|
|
|
number of rows to skip before starting to return rows.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
LIMIT allows you to retrieve just a portion of the rows that are generated
|
|
|
|
|
by the rest of the query. If a limit count is given, no more than that
|
|
|
|
|
many rows will be returned. If an offset is given, that many rows will
|
|
|
|
|
be skipped before starting to return rows.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
When using LIMIT, it is a good idea to use an ORDER BY clause that
|
|
|
|
|
constrains the result rows into a unique order. Otherwise you will get
|
|
|
|
|
an unpredictable subset of the query's rows---you may be asking for
|
|
|
|
|
the tenth through twentieth rows, but tenth through twentieth in what
|
|
|
|
|
ordering? You don't know what ordering unless you specify ORDER BY.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
As of <productname>PostgreSQL</productname> 7.0, the
|
|
|
|
|
query optimizer takes LIMIT into account when generating a query plan,
|
|
|
|
|
so you are very likely to get different plans (yielding different row
|
|
|
|
|
orders) depending on what you use for LIMIT and OFFSET. Thus, using
|
|
|
|
|
different LIMIT/OFFSET values to select different subsets of a query
|
|
|
|
|
result <emphasis>will give inconsistent results</emphasis> unless
|
|
|
|
|
you enforce a predictable result ordering with ORDER BY. This is not
|
|
|
|
|
a bug; it is an inherent consequence of the fact that SQL does not
|
|
|
|
|
promise to deliver the results of a query in any particular order
|
|
|
|
|
unless ORDER BY is used to constrain the order.
|
|
|
|
|
</para>
|
|
|
|
|
</refsect2>
|
|
|
|
|
|
|
|
|
|
<refsect2 id="SQL-FOR-UPDATE">
|
|
|
|
|
<refsect2info>
|
|
|
|
|
<date>2002-08-28</date>
|
|
|
|
|
</refsect2info>
|
|
|
|
|
<title id="sql-for-update-title">
|
|
|
|
|
FOR UPDATE Clause
|
|
|
|
|
</title>
|
|
|
|
|
<para>
|
|
|
|
|
<synopsis>
|
|
|
|
|
FOR UPDATE [ OF <replaceable class="PARAMETER">tablename</replaceable> [, ...] ]
|
|
|
|
|
</synopsis>
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
FOR UPDATE causes the rows retrieved by the query to be locked as though
|
|
|
|
|
for update. This prevents them from being modified or deleted by other
|
|
|
|
|
transactions until the current transaction ends; that is, other
|
|
|
|
|
transactions that attempt UPDATE, DELETE, or SELECT FOR UPDATE of these
|
|
|
|
|
rows will be blocked until the current transaction ends. Also, if an
|
|
|
|
|
UPDATE, DELETE, or SELECT FOR UPDATE from another transaction has already
|
|
|
|
|
locked a selected row or rows, SELECT FOR UPDATE will wait for the other
|
|
|
|
|
transaction to complete, and will then lock and return the updated row
|
|
|
|
|
(or no row, if the row was deleted). For further discussion see the
|
|
|
|
|
concurrency chapter of the <citetitle>User's Guide</citetitle>.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
If specific tables are named in FOR UPDATE, then only rows coming from
|
|
|
|
|
those tables are locked; any other tables used in the SELECT are simply
|
|
|
|
|
read as usual.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
FOR UPDATE cannot be used in contexts where returned rows can't be clearly
|
|
|
|
|
identified with individual table rows; for example it can't be used with
|
|
|
|
|
aggregation.
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
FOR UPDATE may appear before LIMIT for compatibility with
|
|
|
|
|
pre-7.3 applications. However, it effectively executes after LIMIT,
|
|
|
|
|
and so that is the recommended place to write it.
|
|
|
|
|
</para>
|
|
|
|
|
</refsect2>
|
|
|
|
|
|
|
|
|
|
</refsect1>
|
|
|
|
|
|
|
|
|
|
<refsect1 id="R1-SQL-SELECT-2">
|
|
|
|
|
<title>
|
|
|
|
|
Usage
|
|
|
|
|
</title>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
To join the table <literal>films</literal> with the table
|
|
|
|
|
<literal>distributors</literal>:
|
|
|
|
|
|
|
|
|
|
<programlisting>
|
|
|
|
|
SELECT f.title, f.did, d.name, f.date_prod, f.kind
|
|
|
|
|
FROM distributors d, films f
|
|
|
|
|
WHERE f.did = d.did
|
|
|
|
|
|
|
|
|
|
title | did | name | date_prod | kind
|
|
|
|
|
---------------------------+-----+------------------+------------+----------
|
|
|
|
|
The Third Man | 101 | British Lion | 1949-12-23 | Drama
|
|
|
|
|
The African Queen | 101 | British Lion | 1951-08-11 | Romantic
|
|
|
|
|
Une Femme est une Femme | 102 | Jean Luc Godard | 1961-03-12 | Romantic
|
|
|
|
|
Vertigo | 103 | Paramount | 1958-11-14 | Action
|
|
|
|
|
Becket | 103 | Paramount | 1964-02-03 | Drama
|
|
|
|
|
48 Hrs | 103 | Paramount | 1982-10-22 | Action
|
|
|
|
|
War and Peace | 104 | Mosfilm | 1967-02-12 | Drama
|
|
|
|
|
West Side Story | 105 | United Artists | 1961-01-03 | Musical
|
|
|
|
|
Bananas | 105 | United Artists | 1971-07-13 | Comedy
|
|
|
|
|
Yojimbo | 106 | Toho | 1961-06-16 | Drama
|
|
|
|
|
There's a Girl in my Soup | 107 | Columbia | 1970-06-11 | Comedy
|
|
|
|
|
Taxi Driver | 107 | Columbia | 1975-05-15 | Action
|
|
|
|
|
Absence of Malice | 107 | Columbia | 1981-11-15 | Action
|
|
|
|
|
Storia di una donna | 108 | Westward | 1970-08-15 | Romantic
|
|
|
|
|
The King and I | 109 | 20th Century Fox | 1956-08-11 | Musical
|
|
|
|
|
Das Boot | 110 | Bavaria Atelier | 1981-11-11 | Drama
|
|
|
|
|
Bed Knobs and Broomsticks | 111 | Walt Disney | | Musical
|
|
|
|
|
(17 rows)
|
|
|
|
|
</programlisting>
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
To sum the column <literal>len</literal> of all films and group
|
|
|
|
|
the results by <literal>kind</literal>:
|
|
|
|
|
|
|
|
|
|
<programlisting>
|
|
|
|
|
SELECT kind, SUM(len) AS total FROM films GROUP BY kind;
|
|
|
|
|
|
|
|
|
|
kind | total
|
|
|
|
|
----------+-------
|
|
|
|
|
Action | 07:34
|
|
|
|
|
Comedy | 02:58
|
|
|
|
|
Drama | 14:28
|
|
|
|
|
Musical | 06:42
|
|
|
|
|
Romantic | 04:38
|
|
|
|
|
(5 rows)
|
|
|
|
|
</programlisting>
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
To sum the column <literal>len</literal> of all films, group
|
|
|
|
|
the results by <literal>kind</literal> and show those group totals
|
|
|
|
|
that are less than 5 hours:
|
|
|
|
|
|
|
|
|
|
<programlisting>
|
|
|
|
|
SELECT kind, SUM(len) AS total
|
|
|
|
|
FROM films
|
|
|
|
|
GROUP BY kind
|
|
|
|
|
HAVING SUM(len) < INTERVAL '5 hour';
|
|
|
|
|
|
|
|
|
|
kind | total
|
|
|
|
|
----------+-------
|
|
|
|
|
Comedy | 02:58
|
|
|
|
|
Romantic | 04:38
|
|
|
|
|
(2 rows)
|
|
|
|
|
</programlisting>
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
The following two examples are identical ways of sorting the individual
|
|
|
|
|
results according to the contents of the second column
|
|
|
|
|
(<literal>name</literal>):
|
|
|
|
|
|
|
|
|
|
<programlisting>
|
|
|
|
|
SELECT * FROM distributors ORDER BY name;
|
|
|
|
|
SELECT * FROM distributors ORDER BY 2;
|
|
|
|
|
|
|
|
|
|
did | name
|
|
|
|
|
-----+------------------
|
|
|
|
|
109 | 20th Century Fox
|
|
|
|
|
110 | Bavaria Atelier
|
|
|
|
|
101 | British Lion
|
|
|
|
|
107 | Columbia
|
|
|
|
|
102 | Jean Luc Godard
|
|
|
|
|
113 | Luso films
|
|
|
|
|
104 | Mosfilm
|
|
|
|
|
103 | Paramount
|
|
|
|
|
106 | Toho
|
|
|
|
|
105 | United Artists
|
|
|
|
|
111 | Walt Disney
|
|
|
|
|
112 | Warner Bros.
|
|
|
|
|
108 | Westward
|
|
|
|
|
(13 rows)
|
|
|
|
|
</programlisting>
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
This example shows how to obtain the union of the tables
|
|
|
|
|
<literal>distributors</literal> and
|
|
|
|
|
<literal>actors</literal>, restricting the results to those that begin
|
|
|
|
|
with letter W in each table. Only distinct rows are wanted, so the
|
|
|
|
|
ALL keyword is omitted:
|
|
|
|
|
|
|
|
|
|
<programlisting>
|
|
|
|
|
distributors: actors:
|
|
|
|
|
did | name id | name
|
|
|
|
|
-----+-------------- ----+----------------
|
|
|
|
|
108 | Westward 1 | Woody Allen
|
|
|
|
|
111 | Walt Disney 2 | Warren Beatty
|
|
|
|
|
112 | Warner Bros. 3 | Walter Matthau
|
|
|
|
|
... ...
|
|
|
|
|
|
|
|
|
|
SELECT distributors.name
|
|
|
|
|
FROM distributors
|
|
|
|
|
WHERE distributors.name LIKE 'W%'
|
|
|
|
|
UNION
|
|
|
|
|
SELECT actors.name
|
|
|
|
|
FROM actors
|
|
|
|
|
WHERE actors.name LIKE 'W%';
|
|
|
|
|
|
|
|
|
|
name
|
|
|
|
|
----------------
|
|
|
|
|
Walt Disney
|
|
|
|
|
Walter Matthau
|
|
|
|
|
Warner Bros.
|
|
|
|
|
Warren Beatty
|
|
|
|
|
Westward
|
|
|
|
|
Woody Allen
|
Attached are two patches to implement and document anonymous composite
types for Table Functions, as previously proposed on HACKERS. Here is a
brief explanation:
1. Creates a new pg_type typtype: 'p' for pseudo type (currently either
'b' for base or 'c' for catalog, i.e. a class).
2. Creates new builtin type of typtype='p' named RECORD. This is the
first of potentially several pseudo types.
3. Modify FROM clause grammer to accept:
SELECT * FROM my_func() AS m(colname1 type1, colname2 type1, ...)
where m is the table alias, colname1, etc are the column names, and
type1, etc are the column types.
4. When typtype == 'p' and the function return type is RECORD, a list
of column defs is required, and when typtype != 'p', it is
disallowed.
5. A check was added to ensure that the tupdesc provide via the parser
and the actual return tupdesc match in number and type of
attributes.
When creating a function you can do:
CREATE FUNCTION foo(text) RETURNS setof RECORD ...
When using it you can do:
SELECT * from foo(sqlstmt) AS (f1 int, f2 text, f3 timestamp)
or
SELECT * from foo(sqlstmt) AS f(f1 int, f2 text, f3 timestamp)
or
SELECT * from foo(sqlstmt) f(f1 int, f2 text, f3 timestamp)
Included in the patches are adjustments to the regression test sql and
expected files, and documentation.
p.s.
This potentially solves (or at least improves) the issue of builtin
Table Functions. They can be bootstrapped as returning RECORD, and
we can wrap system views around them with properly specified column
defs. For example:
CREATE VIEW pg_settings AS
SELECT s.name, s.setting
FROM show_all_settings()AS s(name text, setting text);
Then we can also add the UPDATE RULE that I previously posted to
pg_settings, and have pg_settings act like a virtual table, allowing
settings to be queried and set.
Joe Conway
23 years ago
|
|
|
</programlisting>
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
This example shows how to use a table function, both with and without
|
|
|
|
|
a column definition list.
|
|
|
|
|
|
|
|
|
|
<programlisting>
|
|
|
|
|
distributors:
|
|
|
|
|
did | name
|
|
|
|
|
-----+--------------
|
|
|
|
|
108 | Westward
|
|
|
|
|
111 | Walt Disney
|
|
|
|
|
112 | Warner Bros.
|
|
|
|
|
...
|
|
|
|
|
|
|
|
|
|
CREATE FUNCTION distributors(int)
|
|
|
|
|
RETURNS SETOF distributors AS '
|
|
|
|
|
SELECT * FROM distributors WHERE did = $1;
|
|
|
|
|
' LANGUAGE SQL;
|
|
|
|
|
|
|
|
|
|
SELECT * FROM distributors(111);
|
|
|
|
|
did | name
|
|
|
|
|
-----+-------------
|
|
|
|
|
111 | Walt Disney
|
|
|
|
|
(1 row)
|
|
|
|
|
|
|
|
|
|
CREATE FUNCTION distributors_2(int)
|
|
|
|
|
RETURNS SETOF RECORD AS '
|
|
|
|
|
SELECT * FROM distributors WHERE did = $1;
|
|
|
|
|
' LANGUAGE SQL;
|
|
|
|
|
|
|
|
|
|
SELECT * FROM distributors_2(111) AS (f1 int, f2 text);
|
|
|
|
|
f1 | f2
|
|
|
|
|
-----+-------------
|
|
|
|
|
111 | Walt Disney
|
|
|
|
|
(1 row)
|
|
|
|
|
</programlisting>
|
|
|
|
|
</para>
|
|
|
|
|
</refsect1>
|
|
|
|
|
|
|
|
|
|
<refsect1 id="R1-SQL-SELECT-3">
|
|
|
|
|
<title>
|
|
|
|
|
Compatibility
|
|
|
|
|
</title>
|
|
|
|
|
|
|
|
|
|
<refsect2 id="R2-SQL-SELECT-4">
|
|
|
|
|
<refsect2info>
|
|
|
|
|
<date>1998-09-24</date>
|
|
|
|
|
</refsect2info>
|
|
|
|
|
<title>Extensions</title>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
<productname>PostgreSQL</productname> allows one to omit
|
|
|
|
|
the <command>FROM</command> clause from a query. This feature
|
|
|
|
|
was retained from the original PostQUEL query language. It has
|
|
|
|
|
a straightforward use to compute the results of simple expressions:
|
|
|
|
|
|
|
|
|
|
<programlisting>
|
|
|
|
|
SELECT 2+2;
|
|
|
|
|
|
|
|
|
|
?column?
|
|
|
|
|
----------
|
|
|
|
|
4
|
|
|
|
|
</programlisting>
|
|
|
|
|
|
|
|
|
|
Some other SQL databases cannot do this except by introducing a dummy one-row
|
|
|
|
|
table to do the select from. A less obvious use is to abbreviate a
|
|
|
|
|
normal select from one or more tables:
|
|
|
|
|
|
|
|
|
|
<programlisting>
|
|
|
|
|
SELECT distributors.* WHERE distributors.name = 'Westward';
|
|
|
|
|
|
|
|
|
|
did | name
|
|
|
|
|
-----+----------
|
|
|
|
|
108 | Westward
|
|
|
|
|
</programlisting>
|
|
|
|
|
|
|
|
|
|
This works because an implicit FROM item is added for each table that is
|
|
|
|
|
referenced in the query but not mentioned in FROM. While this is a convenient
|
|
|
|
|
shorthand, it's easy to misuse. For example, the query
|
|
|
|
|
<programlisting>
|
|
|
|
|
SELECT distributors.* FROM distributors d;
|
|
|
|
|
</programlisting>
|
|
|
|
|
is probably a mistake; most likely the user meant
|
|
|
|
|
<programlisting>
|
|
|
|
|
SELECT d.* FROM distributors d;
|
|
|
|
|
</programlisting>
|
|
|
|
|
rather than the unconstrained join
|
|
|
|
|
<programlisting>
|
|
|
|
|
SELECT distributors.* FROM distributors d, distributors distributors;
|
|
|
|
|
</programlisting>
|
|
|
|
|
that he will actually get. To help detect this sort of mistake,
|
|
|
|
|
<Productname>PostgreSQL</Productname> 7.1
|
|
|
|
|
and later will warn if the implicit-FROM feature is used in a query that also
|
|
|
|
|
contains an explicit FROM clause.
|
|
|
|
|
|
|
|
|
|
</para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
The table-function feature is a <productname>PostgreSQL</productname>
|
|
|
|
|
extension.
|
|
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</para>
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</refsect2>
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<refsect2 id="R2-SQL-SELECT-5">
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<refsect2info>
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<date>1998-09-24</date>
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</refsect2info>
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<title>
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<acronym>SQL92</acronym>
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</title>
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<para>
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</para>
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<refsect3 id="R3-SQL-SELECT-1">
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<refsect3info>
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<date>1998-04-15</date>
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</refsect3info>
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<title>
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|
SELECT Clause
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</title>
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<para>
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|
In the <acronym>SQL92</acronym> standard, the optional keyword <literal>AS</>
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is just noise and can be
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omitted without affecting the meaning.
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The <productname>PostgreSQL</productname> parser requires this keyword when
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renaming output columns because the type extensibility features lead to
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parsing ambiguities
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in this context. <literal>AS</literal> is optional in FROM items, however.</para>
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<para>
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The DISTINCT ON phrase is not part of <acronym>SQL92</acronym>.
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Nor are LIMIT and OFFSET.
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</para>
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<para>
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In <acronym>SQL92</acronym>, an ORDER BY clause may only use result
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column names or numbers, while a GROUP BY clause may only use input
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column names.
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<productname>PostgreSQL</productname> extends each of these clauses to
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allow the other choice as well (but it uses the standard's interpretation
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if there is ambiguity).
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|
<productname>PostgreSQL</productname> also allows both clauses to specify
|
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|
arbitrary expressions. Note that names appearing in an expression will
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|
always be taken as input-column names, not as result-column names.
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|
</para>
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</refsect3>
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|
<refsect3 id="R3-SQL-UNION-1">
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|
<refsect3info>
|
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|
|
|
<date>1998-09-24</date>
|
|
|
|
|
</refsect3info>
|
|
|
|
|
<title>
|
|
|
|
|
UNION/INTERSECT/EXCEPT Clause
|
|
|
|
|
</title>
|
|
|
|
|
<para>
|
|
|
|
|
The <acronym>SQL92</acronym> syntax for UNION/INTERSECT/EXCEPT allows an
|
|
|
|
|
additional CORRESPONDING BY option:
|
|
|
|
|
<synopsis>
|
|
|
|
|
<replaceable class="PARAMETER">table_query</replaceable> UNION [ALL]
|
|
|
|
|
[CORRESPONDING [BY (<replaceable class="PARAMETER">column</replaceable> [,...])]]
|
|
|
|
|
<replaceable class="PARAMETER">table_query</replaceable>
|
|
|
|
|
</synopsis></para>
|
|
|
|
|
|
|
|
|
|
<para>
|
|
|
|
|
The CORRESPONDING BY clause is not supported by
|
|
|
|
|
<productname>PostgreSQL</productname>.
|
|
|
|
|
</para>
|
|
|
|
|
</refsect3>
|
|
|
|
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|
</refsect2>
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</refsect1>
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</refentry>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: sgml
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sgml-omittag:nil
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sgml-shorttag:t
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sgml-minimize-attributes:nil
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sgml-always-quote-attributes:t
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sgml-indent-step:1
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sgml-indent-data:t
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sgml-parent-document:nil
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sgml-default-dtd-file:"../reference.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:"/usr/lib/sgml/catalog"
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sgml-local-ecat-files:nil
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End:
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-->
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