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Diffstat (limited to 'doc/src/sgml/trigger.sgml')
| -rw-r--r-- | doc/src/sgml/trigger.sgml | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/doc/src/sgml/trigger.sgml b/doc/src/sgml/trigger.sgml index 8f83e6a47c8..c43dbc9786e 100644 --- a/doc/src/sgml/trigger.sgml +++ b/doc/src/sgml/trigger.sgml @@ -53,15 +53,21 @@ <para> On views, triggers can be defined to execute instead of <command>INSERT</command>, <command>UPDATE</command>, or - <command>DELETE</command> operations. <literal>INSTEAD OF</literal> triggers + <command>DELETE</command> operations. + Such <literal>INSTEAD OF</literal> triggers are fired once for each row that needs to be modified in the view. It is the responsibility of the - trigger's function to perform the necessary modifications to the - underlying base tables and, where appropriate, return the modified + trigger's function to perform the necessary modifications to the view's + underlying base table(s) and, where appropriate, return the modified row as it will appear in the view. Triggers on views can also be defined to execute once per <acronym>SQL</acronym> statement, before or after <command>INSERT</command>, <command>UPDATE</command>, or <command>DELETE</command> operations. + However, such triggers are fired only if there is also + an <literal>INSTEAD OF</literal> trigger on the view. Otherwise, + any statement targeting the view must be rewritten into a statement + affecting its underlying base table(s), and then the triggers + that will be fired are the ones attached to the base table(s). </para> <para> |