Some database designers try to avoid such semantic issues by defining OrderID as non-nullable so that it must have a value, even when not part of the primary key. These designers then try to propose ...

A primary key is a field used to uniquely identify every record in the database. Sometime primary ... of staff in the teacher table is Staff ID. A foreign key is a primary key from one table ...

Databases support date logic ... a function or other processing could be defined that verifies a value’s existence. Retaining an infinitude of Foreign Keys may cause future performance bottlenecks as ...