Translating Express to SQL:

: This document describes the procedure used by the fedex sql software to translate an Express schema into the SQL statements which generate a relational database schema for storing STEP data. The program which loads a STEP physical file into the database is stepwf sql and is described in a separate document (Nickerson90). The program uses FED-X, an Express parser, which is documented in (Clark90). The software has been developed as part of the National PDES Testbed effort and is funded by the Computer Aided Logistics Support (CALS) project. Three types of issues are involved in translating Express into a relational database schema: translation of the semantic constructs of Express into the data definition language of SQL, resolution of limitation imposed by the database management system, and development of a data dictionary. The first two are discussed in section 2. First, the constructs of the Express language are translated into relational concepts. The application of this mapping to a particular Express schema, generates the SQL data definition language which is the basis for the database. Secondly issues involving the particular database management system (DBMS) are resolved. Section 3 discusses the data dictionary. The dictionary holds information from the conceptual specification which is not explicitly captured in the SQL schema.