The Operator Mapping between Relational Algebra Operators and CODASYL Based Databases Managed by a CODASYL DBMS.

This thesis is an example of a mapping of a relational algebra query onto a network database. It consists of the requirements, definition, design and implementation of two generic COBOL programs for implementing such a mapping. The first program STOREMAP uses a batch input file to build a data dictionary, on the original network database, which defines the relations of which relational algebra queries may be made. This input file is created by the Data Base Administrator who is the most knowledgeable of the structure of the network database and the relations which would be useful to the databasess users. The second program NETTOREL uses the defined relations in the data dictionary and relational algebra queries created by a user to generate a result relations. Data to be included in a result relation is determined by the data dictionarys definition of the relations contained in an associated query and the criteria set by that query. This original effort shows that the theory for such an operator mapping is valid. Further efforts would be needed to make this implementation user friendly and therefore useful. Author