Dtabase Structure

Because of large amount of information, database systems play a vital role in variant process planning systems. A database contains a group of cross-referenced data files. The database contains all information necessary for its application and can be accessed to by several different programs for specific applications. There are three approaches to build a database: hierarchical, network and relational.

The hierarchical approach is frequently used to design the database in the VP system. Given figure shows a hierarchy of the data. Each family is accessed by its family number. A standard plan is associated with each family and is represented by operation code sequence (OP Code). In the sequence each OP Code has an associated OP-plan stored in a lower level. Data for each of level are stored in a file. Therefore, a VP requires three files namely, a family matrix file, a standard plan file and an Op-file.

Figure : Data Hierarchy