Data Integrity

Data Integrity

1. SQL and integrity

   • Data entry/modification
     • constraints
   • Business rules
     • Triggers
   • Transaction support
     • Transactions
       • COMMIT
       • Rollback

2. Referential integrity

   • A foreign key must match a primary key in another relation A foreign key mus tbe null
   • ON DELETE RESTRICT
     • The record in parent table can be deleted only if it is not referred by child table records
   • ON DELETE SET NULL
     • Deleting the record in parent table, the value of this record in child table will be put to "Null"
   • ON DELETE CASCADE
     • Deleting the record in parent table, the record in child table which refers to this will be deleted also