BEFORE triggers let an application call an Ingres database procedure before a triggering operation (INSERT, UPDATE, or DELETE) is executed. The procedure can change the values of columns in rows being inserted or updated, or can inhibit the deletion of rows, depending on their contents. In the CREATE RULE statement, the keyword BEFORE can be used in defining the table condition that triggers the rule.

In addition, in the CREATE PROCEDURE statement, you can optionally assign formal parameters a mode: IN, OUT, or INOUT. For OUT and INOUT parameters, modified parameter values can be passed back to the calling procedure or triggering operation.

For details, see the SQL Reference Guide and Database Administrator Guide.