Action upon update

Specifies what action is to take place on the dependent tables when a row of the parent table is updated.

No Action
Specifies that the row in the parent table can be updated if no other row depends on it. If a dependent row exists in the relationship, the UPDATE fails. The check for dependent rows is performed at the end of the statement.

RestrictSpecifies that the row in the parent table can be updated if no other row depends on it. If a dependent row exists in the relationship, the UPDATE fails. The check for dependent rows is performed immediately.