Relational Database technology - IBM Mainframe

We had a brief discussion about relational databases in Chapter 5. The foundations of Relational Database technology was laid by Dr. E.F. Codd, who in his paper 'A Relational Model of Data for Large Shared Data Banks' laid the basic principles of the RDBMS. Codd was working for IBM at their San Jose Research Lab in California. He laid down certain principles of database management, referred to as relational model. These principles were soon applied to experimental systems, and a start was made on the design of a database language that would interact with such systems.

In 1974, Chamberlain and Boyce, also from IBM San Jose, read a paper at a database workshop at the University of Ann Arbor, Michigan. This paper introduced the database language SEQUEL, which was implemented by IBM in 1974 - 75 as the prototype language SEQUEL-XRM.

The first attempt at a larger scale implementation of Codd'-s. relational model was IBM's System R. This system used a revised version of the SEQUEL called SEQUEL/2. In 1977, System R became operational and SEQUEL became SQL.

System R was a success and relational ideas became accessible to general computer users. This was mainly due to the writings of C.J. Date (again from IBM), who in his book 'An Introduction to Database Systems' provided a clear and readable introduction. The 7th edition of this book was published in 2000 and is highly recommended to the reader as an excellent intermediate text on database management systems.

At present there are many implementations of the relational technology. DB2, ORACLE, Sybase, MS-SQL Server, MS-Access, Ingress etc. are some among them. Relational systems are now available in all sizes and shapes and for all sizes of computers.

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