Edgar F. Codd, proposed thirteen rules (0 to 12) to define what is require d from a DBMS in order for it to be considered relational. Currently there is no commercial database management system which fully satisfies all the CODD’s rules.
- Rule No. 0 – Foundation rule – The system must qualify as relational both as a database and as a management system.
- Rule No. 1 – The information rule – All information in the database should be represented in one and only one way as values in a table.
- Rule No. 6 – The view updating rule – All views that are theoretically updateable are also updateable by the system.
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