a block structured query language for accessing a relational data base
This paper describes a B lock S tructured Q uery L anguage (BSQL) to be used with relational data bases. The syntax of the language is presented and discussed. Facilities of the language are illustrated by examples of actual queries. In particular we demonstrate the ability of BSQL to obtain useful information from a relational data base that is incomplete. A relational calculus is then presented which forms a basis for a formalism which precisely describes the semantics of BSQL. Finally, comparative examples with other query languages are given.
query languages data base languages