What is Relational Data Model ?
Introduction Before 1970 most the database system were based on two models i.e. Hierarchical Model or Network Model Dr. Codd (IBM Scientist) proposed a relational Data Model in 1970. A RDBMS is a Database Management system which is based on relational model as introduced by Dr. Codd. It should satisfy Codd 12 rules but in practice there is no DBMS that satisfies all these rules. Today, popular RDBMS are: Microsoft Access MSSQL MYSQL Oracle Sybase DB2 Informix FoxBASE, FoxPro & Clipper etc. Overview of CODD’s 12 rules Dr. E.F. Codd is an IBM researcher who first developed the relational data model in 1970. In 1985 Dr. Codd published a list of 12 rules that define an ideal relational database and has provided a guideline for the design of all relational database system Codd's Rules Rule 1 : The information Rule This rule simply requires that all Information/ data should be presented in table form. ...