CODD'S RULES Dr.Edgar Frank Codd (Augest 19,1923 – April 18,2003) was a Computer Scientist who working in IBM .And he invented the Relational Model for Database Management based on relational model ,the Relational database was created in 1985.And E.F.Codd proposed 13 rules for Relational database .Every Relational database table should follow the Codd rules.Because that table is a pure Relational database table.DBMS meets these rules is called RDBMS. In codd's rule: 1.We follow any 5-6 rules it qualified to be a Database Management system(DBMS). 2.We follow any 7-9 rules it qualified to be a Semi-Relational Database Management system(Semi-RDBMS). ...