E. F. Codd's Rules
- Data is Presented in Tables
- Data is logically accessible
- Nulls are treated uniformly as Unknown
- Database is self describing
- A simple language is used to communicate with DBMS
- Provides alternatives for viewing
- Support set based or relational operations
- Physical Data Independence
- Logical Data Independence
- Data Integrity is a Function of the DBMS
- Support Distributed Operation
- Data Integrity cannot subverted
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