Codd's Twelve Rules / Codd's Twelve Commandments / Relational Model Foundation Principles
Can we say “any database that supports SQL is a relational database”? No. At least, not completely. We need certain foundation principle to make this assessment. For any system to be called a relational database management system, the relational capabilities must be able to manage it completely. Edgar F. Codd, a pioneer of the relational model for databases, designed Codd’s twelve rules to define what is required from a database management system in order for it to be considered relational, i.e., a relational database management system (RDBMS).
Those rules are listed below and the links will lead you to the description pages of those rules.
- Rule 1 : Information Rule
- Rule 2 : Guaranteed Access Rule
- Rule 3 : Systematic treatment of NULL values
- Rule 5 : Comprehensive Data Sublanguage Rule
- Rule 6 : View Updating Rule
- Rule 8 : Physical Data Independence
- Rule 9 : Logical Data Independence
- Rule 10: Integrity Independence
- Rule 11: Distribution Independence
- Rule 12: Non-Subversion Rule
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