diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/ref/select.sgml | 28 |
1 files changed, 21 insertions, 7 deletions
diff --git a/doc/src/sgml/ref/select.sgml b/doc/src/sgml/ref/select.sgml index d6a17cc7a44..f9f83f34f70 100644 --- a/doc/src/sgml/ref/select.sgml +++ b/doc/src/sgml/ref/select.sgml @@ -34,7 +34,7 @@ PostgreSQL documentation <synopsis> [ WITH [ RECURSIVE ] <replaceable class="parameter">with_query</replaceable> [, ...] ] SELECT [ ALL | DISTINCT [ ON ( <replaceable class="parameter">expression</replaceable> [, ...] ) ] ] - * | <replaceable class="parameter">expression</replaceable> [ [ AS ] <replaceable class="parameter">output_name</replaceable> ] [, ...] + [ * | <replaceable class="parameter">expression</replaceable> [ [ AS ] <replaceable class="parameter">output_name</replaceable> ] [, ...] ] [ FROM <replaceable class="parameter">from_item</replaceable> [, ...] ] [ WHERE <replaceable class="parameter">condition</replaceable> ] [ GROUP BY <replaceable class="parameter">expression</replaceable> [, ...] ] @@ -1740,7 +1740,8 @@ SELECT 2+2; following query is invalid: <programlisting> SELECT distributors.* WHERE distributors.name = 'Westward'; -</programlisting><productname>PostgreSQL</productname> releases prior to +</programlisting> + <productname>PostgreSQL</productname> releases prior to 8.1 would accept queries of this form, and add an implicit entry to the query's <literal>FROM</literal> clause for each table referenced by the query. This is no longer allowed. @@ -1748,6 +1749,19 @@ SELECT distributors.* WHERE distributors.name = 'Westward'; </refsect2> <refsect2> + <title>Empty <literal>SELECT</literal> Lists</title> + + <para> + The list of output expressions after <literal>SELECT</literal> can be + empty, producing a zero-column result table. + This is not valid syntax according to the SQL standard. + <productname>PostgreSQL</productname> allows it to be consistent with + allowing zero-column tables. + However, an empty list is not allowed when <literal>DISTINCT</> is used. + </para> + </refsect2> + + <refsect2> <title>Omitting the <literal>AS</literal> Key Word</title> <para> @@ -1809,10 +1823,6 @@ SELECT distributors.* WHERE distributors.name = 'Westward'; <productname>PostgreSQL</productname> treats <literal>UNNEST()</> the same as other set-returning functions. </para> - - <para> - <literal>ROWS FROM( ... )</> is an extension of the SQL standard. - </para> </refsect2> <refsect2> @@ -1910,9 +1920,13 @@ SELECT distributors.* WHERE distributors.name = 'Westward'; <title>Nonstandard Clauses</title> <para> - The clause <literal>DISTINCT ON</literal> is not defined in the + <literal>DISTINCT ON ( ... )</literal> is an extension of the SQL standard. </para> + + <para> + <literal>ROWS FROM( ... )</> is an extension of the SQL standard. + </para> </refsect2> </refsect1> </refentry> |