Table of Contents
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.
Foreign Key and ObjectPtr
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.
ObjectPtr
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.
BinaryLink
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.
You can use this action for binary link of 1:M kind. For symmetric links of 1:1 and M:M kind this can be used only if VLink.Owner is specified.