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