Cascade is a referential integrity setting that can be applied to primary key tables, which maintains primary/foreign key relationships automatically. The Cascade options include:
•Update
•Delete
Cascading updates enforce that when a primary key value is updated, the corresponding value in the foreign key table(s) will also be updated.
Cascading deletes enforce that when a primary key value is deleted, the corresponding value in the foreign key table(s) will also be deleted.
By not specifying either Update or Delete, both Cascade restrictions will be enforced upon the primary/foreign key tables and will prevent the values from being altered or deleted in the primary key table.
Separate Update and Delete data restrictions can allow a Cascade to be enforced for records that are updated, but not enforced when records are deleted, in order to avoid an accidental or undesired record delete. For example, if you either Update or Delete a primary key value from a table, the corresponding foreign key values are updated or deleted automatically. A Cascade can applied to Update, Delete or both to specific primary keys.
Cascade can be defined through the R:BASE command syntax using either the CREATE TABLE or ALTER TABLE commands. Cascade can also be set within the Data Designer when viewing the table properties.
Notes:
•Cascade can only be added to tables with defined Primary Keys.
•Cascade can be set to Update, Delete, or both.
