diff options
| -rw-r--r-- | doc/src/sgml/ref/select.sgml | 46 |
1 files changed, 24 insertions, 22 deletions
diff --git a/doc/src/sgml/ref/select.sgml b/doc/src/sgml/ref/select.sgml index 410c80e730b..1f9538f2feb 100644 --- a/doc/src/sgml/ref/select.sgml +++ b/doc/src/sgml/ref/select.sgml @@ -59,7 +59,9 @@ 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> [, ...] ) [ AS <replaceable class="parameter">join_using_alias</replaceable> ] ] + <replaceable class="parameter">from_item</replaceable> <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> ] } + <replaceable class="parameter">from_item</replaceable> NATURAL <replaceable class="parameter">join_type</replaceable> <replaceable class="parameter">from_item</replaceable> + <replaceable class="parameter">from_item</replaceable> CROSS JOIN <replaceable class="parameter">from_item</replaceable> <phrase>and <replaceable class="parameter">grouping_element</replaceable> can be one of:</phrase> @@ -600,19 +602,15 @@ TABLE [ ONLY ] <replaceable class="parameter">table_name</replaceable> [ * ] <listitem> <para><literal>FULL [ OUTER ] JOIN</literal></para> </listitem> - <listitem> - <para><literal>CROSS JOIN</literal></para> - </listitem> </itemizedlist> For the <literal>INNER</literal> and <literal>OUTER</literal> join types, a join condition must be specified, namely exactly one of - <literal>NATURAL</literal>, <literal>ON <replaceable - class="parameter">join_condition</replaceable></literal>, or + <literal>ON <replaceable + class="parameter">join_condition</replaceable></literal>, <literal>USING (<replaceable - class="parameter">join_column</replaceable> [, ...])</literal>. - See below for the meaning. For <literal>CROSS JOIN</literal>, - none of these clauses can appear. + class="parameter">join_column</replaceable> [, ...])</literal>, + or <literal>NATURAL</literal>. See below for the meaning. </para> <para> @@ -623,17 +621,9 @@ TABLE [ ONLY ] <replaceable class="parameter">table_name</replaceable> [ * ] In the absence of parentheses, <literal>JOIN</literal>s nest left-to-right. In any case <literal>JOIN</literal> binds more tightly than the commas separating <literal>FROM</literal>-list items. - </para> - - <para><literal>CROSS JOIN</literal> and <literal>INNER JOIN</literal> - produce a simple Cartesian product, the same result as you get from - listing the two tables at the top level of <literal>FROM</literal>, - but restricted by the join condition (if any). - <literal>CROSS JOIN</literal> is equivalent to <literal>INNER JOIN ON - (TRUE)</literal>, 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 <literal>FROM</literal> and - <literal>WHERE</literal>. + All the <literal>JOIN</literal> options are just a notational + convenience, since they do nothing you couldn't do with plain + <literal>FROM</literal> and <literal>WHERE</literal>. </para> <para><literal>LEFT OUTER JOIN</literal> returns all rows in the qualified @@ -715,6 +705,19 @@ TABLE [ ONLY ] <replaceable class="parameter">table_name</replaceable> [ * ] </varlistentry> <varlistentry> + <term><literal>CROSS JOIN</literal></term> + <listitem> + <para> + <literal>CROSS JOIN</literal> is equivalent to <literal>INNER JOIN ON + (TRUE)</literal>, that is, no rows are removed by qualification. + They produce a simple Cartesian product, the same result as you get from + listing the two tables at the top level of <literal>FROM</literal>, + but restricted by the join condition (if any). + </para> + </listitem> + </varlistentry> + + <varlistentry> <term><literal>LATERAL</literal></term> <listitem> <para> @@ -1754,8 +1757,7 @@ SELECT * FROM <replaceable class="parameter">name</replaceable> <programlisting> SELECT f.title, f.did, d.name, f.date_prod, f.kind - FROM distributors d, films f - WHERE f.did = d.did + FROM distributors d JOIN films f USING (did); title | did | name | date_prod | kind -------------------+-----+--------------+------------+---------- |