E.F Codd was a Computer Scientist who invented a Relational Model for Database Management. Based on the relational model, Relation database was created. Codd proposed 13 rules popularly known as Codd’s 12 rules to test DBMS’s concept against his relational model. Codd’s rule actually defines what quality a DBMS requires in order to become a Relational Database Management System(RDBMS). Till now, there is hardly any commercial product that follows all the 13 Codd’s rules. Even Oracle follows only eight and half out(8.5) of 13. The Codd’s 12 rules are as follows.
Rule zero (Yes, there is a Rule 0!) :
Rule 1: Information rule
Rule 2: Guaranteed Access
Rule 3: Systematic treatment of NULL
Rule 4: Active Online Catalog
Rule 5: Powerful language
Rule 6: View Update rule
Rule 7: Relational Level Operation
Rule 8: Physical Data Independence
The physical storage of data should not matter to the system. If say, some file supporting table were renamed or moved from one disk to another, it should not affect the application.
Rule 9: Logical Data Independence
Rule 10: Integrity Independence
Rule 11: Distribution Independence
Rule 12: Nonsubversion Rule
If you like the article please do like or leave a comment, I feel happy that my effort has been appreciated.