diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/inherit.sgml | 53 |
1 files changed, 52 insertions, 1 deletions
diff --git a/doc/src/sgml/inherit.sgml b/doc/src/sgml/inherit.sgml index 774795f94d9..bb0a4d9c7a6 100644 --- a/doc/src/sgml/inherit.sgml +++ b/doc/src/sgml/inherit.sgml @@ -1,5 +1,5 @@ <!-- -$Header: /cvsroot/pgsql/doc/src/sgml/Attic/inherit.sgml,v 1.10 2000/06/22 22:31:15 petere Exp $ +$Header: /cvsroot/pgsql/doc/src/sgml/Attic/inherit.sgml,v 1.11 2000/07/02 22:00:23 momjian Exp $ --> <chapter id="inherit"> @@ -96,6 +96,57 @@ CREATE TABLE capitals UNDER cities ( <command>UPDATE</command> and <command>DELETE</command> -- support this <quote>ONLY</quote> notation. </para> + + <para> + In some cases you may wish to know which table a particular tuple + originated from. There is a system attribute called + <quote>TABLEOID</quote> in each table which can tell you the + originating table: + + <programlisting> + SELECT c.tableoid, c.name, c.altitude + FROM cities c + WHERE c.altitude > 500; + </programlisting> + + which returns: + + <programlisting> ++---------+----------+----------+ +|tableoid |name | altitude | ++---------+----------+----------+ +|37292 |Las Vegas | 2174 | ++---------+----------+----------+ +|37280 |Mariposa | 1953 | ++---------+----------+----------+ +|37280 |Madison | 845 | ++---------+----------+----------+ + </programlisting> + + If you do a join with pg_class you can see the actual table name: + + <programlisting> + SELECT p.relname, c.name, c.altitude + FROM cities c, pg_class p + WHERE c.altitude > 500 and c.tableoid = p.oid; + </programlisting> + + which returns: + + <programlisting> ++---------+----------+----------+ +|relname |name | altitude | ++---------+----------+----------+ +|capitals |Las Vegas | 2174 | ++---------+----------+----------+ +|cities |Mariposa | 1953 | ++---------+----------+----------+ +|cities |Madison | 845 | ++---------+----------+----------+ + </programlisting> + + </para> + <note> <title>Deprecated</title> <para> |