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+$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_trigger.sgml,v 1.19 2001/11/29 22:18:14 momjian Exp $
Postgres documentation
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</para>
<para>
- The trigger can be specified to fire either before BEFORE the
- operation is attempted on a tuple (before constraints
- are checked and the <command>INSERT</command>, <command>UPDATE</command> or
- <command>DELETE</command> is attempted) or
- AFTER the operation has been attempted (e.g., after constraints
- are checked and the <command>INSERT</command>,
- <command>UPDATE</command> or <command>DELETE</command> has
- completed). If the
- trigger fires before the event, the trigger may
- skip the operation for the current tuple, or change the tuple
- being inserted (for <command>INSERT</command> and
- <command>UPDATE</command> operations only). If
- the trigger fires after the event, all changes, including the
- last insertion, update, or deletion, are <quote>visible</quote> to the trigger.
+ The trigger can be specified to fire either before BEFORE the
+ operation is attempted on a tuple (before constraints are checked and
+ the <command>INSERT</command>, <command>UPDATE</command> or
+ <command>DELETE</command> is attempted) or AFTER the operation has
+ been attempted (e.g., after constraints are checked and the
+ <command>INSERT</command>, <command>UPDATE</command> or
+ <command>DELETE</command> has completed). If the trigger fires before
+ the event, the trigger may skip the operation for the current tuple,
+ or change the tuple being inserted (for <command>INSERT</command> and
+ <command>UPDATE</command> operations only). If the trigger fires
+ after the event, all changes, including the last insertion, update,
+ or deletion, are <quote>visible</quote> to the trigger.
+ </para>
+ <para>
+ <command>SELECT</command> does not modify any rows so you can not
+ create <command>SELECT</command> triggers.
</para>
<para>