E.F. Codd's Rules

 1. Information Representation
 2. Guaranteed Access
 3. Systematic treatment of Null values
 4. View Updation (80 % )
 5. Comprehensive Data sub language
 6. High level Insert,Update,Delete
 7. Data description rule
 8. Data distribution rule
 9. Physical Data Independence
 10. Logical Data Independence
 11. Data Integrity rules ( Constraints )
 12. Non sub version rule