A pure relational database, as designed by Codd ... and tables are related through foreign keys. SQL is used to declare the data to be returned, and a SQL query processor and query optimizer ...

By using cascading referential integrity constraints, you can define the actions that SQL Server 2005 takes when a user tries to delete or update a key to which existing foreign keys point.

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 ...

Retaining an infinitude of Foreign Keys may cause future performance bottlenecks as transactional volume will get a performance hit by maintaining all those foreign keys and the indexes behind them.