diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/ref/select.sgml | 16 |
1 files changed, 14 insertions, 2 deletions
diff --git a/doc/src/sgml/ref/select.sgml b/doc/src/sgml/ref/select.sgml index 9c5cf50ef0c..fa676b1698d 100644 --- a/doc/src/sgml/ref/select.sgml +++ b/doc/src/sgml/ref/select.sgml @@ -59,7 +59,7 @@ SELECT [ ALL | DISTINCT [ ON ( <replaceable class="parameter">expression</replac [ LATERAL ] <replaceable class="parameter">function_name</replaceable> ( [ <replaceable class="parameter">argument</replaceable> [, ...] ] ) AS ( <replaceable class="parameter">column_definition</replaceable> [, ...] ) [ LATERAL ] ROWS FROM( <replaceable class="parameter">function_name</replaceable> ( [ <replaceable class="parameter">argument</replaceable> [, ...] ] ) [ AS ( <replaceable class="parameter">column_definition</replaceable> [, ...] ) ] [, ...] ) [ WITH ORDINALITY ] [ [ AS ] <replaceable class="parameter">alias</replaceable> [ ( <replaceable class="parameter">column_alias</replaceable> [, ...] ) ] ] - <replaceable class="parameter">from_item</replaceable> [ NATURAL ] <replaceable class="parameter">join_type</replaceable> <replaceable class="parameter">from_item</replaceable> [ ON <replaceable class="parameter">join_condition</replaceable> | USING ( <replaceable class="parameter">join_column</replaceable> [, ...] ) ] + <replaceable class="parameter">from_item</replaceable> [ NATURAL ] <replaceable class="parameter">join_type</replaceable> <replaceable class="parameter">from_item</replaceable> [ ON <replaceable class="parameter">join_condition</replaceable> | USING ( <replaceable class="parameter">join_column</replaceable> [, ...] ) [ AS <replaceable class="parameter">join_using_alias</replaceable> ] ] <phrase>and <replaceable class="parameter">grouping_element</replaceable> can be one of:</phrase> @@ -676,7 +676,7 @@ TABLE [ ONLY ] <replaceable class="parameter">table_name</replaceable> [ * ] </varlistentry> <varlistentry> - <term><literal>USING ( <replaceable class="parameter">join_column</replaceable> [, ...] )</literal></term> + <term><literal>USING ( <replaceable class="parameter">join_column</replaceable> [, ...] ) [ AS <replaceable class="parameter">join_using_alias</replaceable> ]</literal></term> <listitem> <para> A clause of the form <literal>USING ( a, b, ... )</literal> is @@ -686,6 +686,18 @@ TABLE [ ONLY ] <replaceable class="parameter">table_name</replaceable> [ * ] equivalent columns will be included in the join output, not both. </para> + + <para> + If a <replaceable class="parameter">join_using_alias</replaceable> + name is specified, it provides a table alias for the join columns. + Only the join columns listed in the <literal>USING</literal> clause + are addressable by this name. Unlike a regular <replaceable + class="parameter">alias</replaceable>, this does not hide the names of + the joined tables from the rest of the query. Also unlike a regular + <replaceable class="parameter">alias</replaceable>, you cannot write a + column alias list — the output names of the join columns are the + same as they appear in the <literal>USING</literal> list. + </para> </listitem> </varlistentry> |