Codd's Twelve Rules

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.

Codd’s twelve rules

• Rule 1  : Information Rule

• Rule 2 : Guaranteed Access Rule

• Rule 3 : Systematic treatment of NULL values

• Rule 4 : Dynamic Online Catalog Based on the RelationalModel

• Rule 5 : Comprehensive Data Sublanguage Rule

• Rule 6 : View Updating Rule

• Rule 7 : High level Insert, Update, and Delete

• Rule 8 : Physical Data Independence

• Rule 9 : Logical Data Independence

• Rule 10: Integrity Independence

• Rule 11: Distribution Independence          

• Rule 12: Non-Subversion Rule