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Diffstat (limited to 'doc/src/sgml/syntax.sgml')
| -rw-r--r-- | doc/src/sgml/syntax.sgml | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/doc/src/sgml/syntax.sgml b/doc/src/sgml/syntax.sgml index e8e0da96b95..2ebea7cf34b 100644 --- a/doc/src/sgml/syntax.sgml +++ b/doc/src/sgml/syntax.sgml @@ -1522,6 +1522,19 @@ sqrt(2) The arguments can optionally have names attached. See <xref linkend="sql-syntax-calling-funcs"> for details. </para> + + <note> + <para> + A function that takes a single argument of composite type can + optionally be called using field-selection syntax, and conversely + field selection can be written in functional style. That is, the + notations <literal>col(table)</> and <literal>table.col</> are + interchangeable. This behavior is not SQL-standard but is provided + in <productname>PostgreSQL</> because it allows use of functions to + emulate <quote>computed fields</>. For more information see + <xref linkend="xfunc-sql-composite-functions">. + </para> + </note> </sect2> <sect2 id="syntax-aggregates"> |