IBM System R
System R is a database management system developed by IBM at the San Jose Research Center (now the IBM Almaden Research Center ) . The system was developed in the 1970s as part of a research project. It is historically important because it is the first relational was database management system and the query language SEQUEL (= S tructured E nglish Que ry L anguage) defined from which the SQL query language emerged. Edgar F. Codd was instrumental in laying the foundations for this research work.
System R was already characterized by good transaction performance and had a query optimizer and B-trees as an index method . The System R was tested by some IBM customers, but was never marketed.
As a result of the experience with System R, IBM developed the SQL / DS system and used it for customers from 1981. SQL / DS is the predecessor of the relational database management system DB2 .
Edgar F. Codd's work also inspired other software developers outside of IBM. Larry Ellison founded Software Development Laboratories in 1977 and developed the relational database management system Oracle . Later the name of the database was also adopted as the company name (company).
The SQL query language has established itself as the standard to this day. It was first adopted as a standard by ANSI in 1986 and by ISO in 1987 . In the years that followed, the SQL standard was expanded significantly.