PowerDesigner Pre-Defined Trigger Template Items

PowerDesigner provides pre-defined template items for the trigger templates defined in each DBMS. The Rebuild Triggers function uses both pre-defined and user-defined trigger templates to automatically create triggers for selected tables.

In the pre-defined trigger templates, each pre-defined template item corresponds to a referential integrity constraint. Although a pre-defined template item is defined in a trigger template, it is only generated in a trigger script if it implements the trigger referential integrity defined for a reference. The item is available for generation if it is present on the Template Items tab of a trigger property sheet and will be generated if it is present on the Template Items tab of a trigger template property sheet.

Insert Constraints

The template items below implement referential integrity in insert trigger templates.

Template item	Integrity constraint	Description
DeclInsertChildParentExist InsertChildParentExist	Mandatory parent	Parent must exist when inserting a child
DeclInsertTooManyChildren InsertTooManyChildren	Cannot exceed maximum cardinality constraint	Cannot insert a child if maximum cardinality has been reached
DeclInsertSequenceColumn InsertSequenceColumn	Select value in sequence list for column	Select a value for the column from a list of sequences

Update Constraints

The template items below implement referential integrity in update trigger templates.

Template item	Integrity constraint	Description
`DeclUpdateChildParentExist` `UpdateChildParentExist`	Mandatory parent	Parent must exist when updating a child
`DeclUpdateChildChangeParent` `UpdateChildChangeParent`	Change parent not allowed	Cannot modify parent code in child
`DeclUpdateParentRestrict` `UpdateParentRestrict`	Restrict on update	Cannot modify parent if child exists
`DeclUpdateParentCascade` `UpdateParentCascade`	Cascade on update	Modify parent code in all children
`DeclUpdateChangeColumn` `UpdateChangeColumn`	Non-modifiable column	Cannot modify column
`DeclUpdateParentSetNull` `UpdateParentSetNull`	Set null on update	Set parent code to null in all children
`DeclUpdateParentSetDefault` `UpdateParentSetDefault`	Set default on update	Set parent code to default in all children
`DeclUpdateTooManyChildren` `UpdateTooManyChildren`	Cannot exceed maximum cardinality constraint	Cannot update a child if maximum cardinality has been reached

Delete Constraints

The template items below implement referential integrity in delete trigger templates.

Template item	Integrity constraint	Description
`DeclDeleteParentRestrict` `DeleteParentRestrict`	Restrict on delete	Cannot delete parent if child exists
`DeclDeleteParentCascade` `DeleteParentCascade`	Cascade on delete	Delete parent code in all children
`DeclDeleteParentSetNull` `DeleteParentSetNull`	Set null on delete	Delete in parent sets child to null
`DeclDeleteParentSetDefault` `DeleteParentSetDefault`	Set default on delete	Delete in parent sets child to default

Constraint Messages

You can insert the following template items in any trigger template. They generate error messages that indicate the violation of an integrity constraint.

Template item	Description
UseErrorMsgText	Error handling without a message table
UseErrorMsgTable	Error handling with a message table