A RECURSIVE RELATIONAL DATA BASE STRUCTURE FOR CHEMICAL PROCESS INFORMATION SYSTEMS

Abstract

A comprehensive relational data base structure for chemical processes is proposed. The data base can hold data about the physical attributes of chemical processes and about their reactants and products. By means of a recursive many-to-many relationship, involving a multivalued dependency, the data base also holds data about the breakdown of any process into its subprocesses, their subprocesses, and so on, to any desired breakdown level. The relational data base language SQL can be used. Current releases of SQL do not have facilities for recursive expressions, so that SQL retrieval expressions involving descent to unpredictable subprocess breakdown levels cannot be constructed. This difficulty can be circumvented by the use of multiple SQL expressions. Where molecular substructure data is also needed, then the chemical process data base can be used with a comprehensive relational molecular structure data base.