The Relational Model: Integrity - Database
- Constraints involving more than one relation
- Foreign keys are one type of database constraint
- Every part_number in SupplierOfPart must correspond to a part_number Part
- Simplified double-entry bookkeeping constraint:
- For every tuple in Deposit there must be a tuple in Withdrawal with the same transaction_id
- The value of the amount attribute for the two tuples must be the same