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<chapter id="rules">

<title>The Rule System</title>

</para>

<para>

On the other hand, a trigger that is fired on

<command>INSERT</command> on a view can do the same as a rule: put

the data somewhere else and suppress the insert in the view. But

it cannot do the same thing on <command>UPDATE</command> or

<command>DELETE</command>, because there is no real data in the

view relation that could be scanned, and thus the trigger would

never get called. Only a rule will help.

On the other hand, a trigger cannot be created on views because

there is no real data in a view relation; however INSERT, UPDATE,

and DELETE rules can be created on views.

</para>

<para>