Dr. Edgar F. Codd proposed a set of rules that were intended to define the important characteristics and capabilities of any relational system [Codd 1986]. Today, Codd’s rules are used as a yardstick for what can be expected from a conventional relational DBMS. Though, it is referred to as “Codd’s twelve rules”, in reality there are thirteen rules. The Codd’s rules are summarised in Table 5.1.
|Rule 0||Foundation Rule||A relational database management system must manage the database entirely through its relational capabilities.|
|Rule 1||Information Rule||All information is represented logically by values in tables.|
|Rule 2||Guaranteed Access Rule||Every data value is logically accessible by a combination ...|