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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2008-12-09 20:52:03 +0000 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2008-12-09 20:52:03 +0000 |
| commit | 5932915fef5a3fce0267de390650fd98b4a3d824 (patch) | |
| tree | f2a21790c8dda77ed30efc9857d13a924df47945 | |
| parent | dea81a6cf620528e6c17e9973b32b54e0076cf06 (diff) | |
| download | postgresql-5932915fef5a3fce0267de390650fd98b4a3d824.tar.gz postgresql-5932915fef5a3fce0267de390650fd98b4a3d824.zip | |
Add a specific example of parenthesizing when extracting a field of a
composite column. Might help cut down on future questions...
| -rw-r--r-- | doc/src/sgml/syntax.sgml | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/doc/src/sgml/syntax.sgml b/doc/src/sgml/syntax.sgml index 90aa3b6c9b4..cca44794340 100644 --- a/doc/src/sgml/syntax.sgml +++ b/doc/src/sgml/syntax.sgml @@ -1,4 +1,4 @@ -<!-- $PostgreSQL: pgsql/doc/src/sgml/syntax.sgml,v 1.125 2008/10/29 14:35:04 momjian Exp $ --> +<!-- $PostgreSQL: pgsql/doc/src/sgml/syntax.sgml,v 1.126 2008/12/09 20:52:03 tgl Exp $ --> <chapter id="sql-syntax"> <title>SQL Syntax</title> @@ -1387,7 +1387,18 @@ $1.somecolumn </programlisting> (Thus, a qualified column reference is actually just a special case - of the field selection syntax.) + of the field selection syntax.) An important special case is + extracting a field from a table column that is of a composite type: + +<programlisting> +(compositecol).somefield +(mytable.compositecol).somefield +</programlisting> + + The parentheses are required here to show that + <structfield>compositecol</> is a column name not a table name, + or that <structname>mytable</> is a table name not a schema name + in the second case. </para> </sect2> |