.. _rule_dialog:

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The Rule Dialog
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Use the *Rule* dialog to define or modify a rule for a specified table or view. A PostgreSQL rule allows you to define an additional action that will be performed when a SELECT, INSERT, UPDATE, or DELETE is performed against a table.

The *Rule* dialog organizes the development of a rule through the *General*, and *Definition* tabs. The *SQL* tab displays the SQL code generated by dialog selections.

.. image:: images/rule_general.png
    :alt: Rule dialog general tab

Use the fields in the *General* tab to identify the rule:

* Use the *Name* field to add a descriptive name for the rule. The name will be displayed in the *pgAdmin* tree control. Multiple rules on the same table are applied in alphabetical name order.
* Store notes about the rule in the *Comment* field.

Click the *Definition* tab to continue.

.. image:: images/rule_definition.png
    :alt: Rule dialog definition tab

Use the fields in the *Definition* tab to write parameters:

* Click inside the *Event* field to select the type of event that will invoke the rule; event may be *Select*, *Insert*, *Update*, or *Delete*.
* Move the *Do Instead* switch to *Yes* indicate that the commands should be executed instead of the original command; if Do Instead specifies *No*, the rule will be invoked in addition to the original command.
* Specify a SQL conditional expression that returns a boolean value in the *Condition* editor.
* Provide a command in the *Commands* editor that defines the action performed by the rule.

Click the *SQL* tab to continue.

Your entries in the *Rule* dialog generate a SQL command (see an example below). Use the *SQL* tab for review; revisit or switch tabs to make any changes to the SQL command.

**Example**

The following is an example of the sql command generated by user selections in the *Rule* dialog:

.. image:: images/rule_sql.png
    :alt: Rule dialog sql tab

The example sends a notification when an UPDATE executes against a table.

* Click the *Info* button (i) to access online help. View context-sensitive help in the *Tabbed browser*, where a new tab displays the PostgreSQL core documentation.
* Click the *Save* button to save work.
* Click the *Cancel* button to exit without saving work.
* Click the *Reset* button to restore configuration parameters.