Action ON DELETE

The ONE DELETE Action specifies what should happens with Child-records when you delete a parent record. With help of this you can control Referential Integrity of your database, thereby enforcing business rules at the database level

When you try DELETE a parent record this raise question: what should happens with its child records? The answer gives the ON DELETE Action of a Link.

You can specify one of the following constants:

• RESTRICT (default). Means that DELETE of parent record is refused if at least one child record exists.

• CASCADE - means that all child records are deleted also.

• SET NULL - means that value of PTR field is set to NULL, i.e. a child record still exists, but do not have parent record.

• SET DEFAULT - means that value of PTR field is set to its default value, i.e. it looks like the child record gets a new parent record.

You can specify one of the following constants:

• RESTRICT (default). Means that DELETE of parent record is refused if at least one child record exists.

• CASCADE - means that all child records are deleted also.

• SET NULL - means that value of PTR field is set to NULL, i.e. a child record still exists, but do not have parent record.

You can specify one of the following constants:

• RESTRICT - (default), means that DELETE of parent record is refused if at least one child record exists.

• CASCADE - means that all child records are deleted also.