Database Users

1. The database users fall into several categories:
   • Application programmers are computer professionals interacting with the system through DML calls embedded in a program written in a host language (e.g. C, PL/1, Pascal).
     • These programs are called application programs.
     • The DML precompiler converts DML calls (prefaced by a special character like $, #, etc.) to normal procedure calls in a host language.

     • The host language compiler then generates the object code.
     • Some special types of programming languages combine Pascal-like control structures with control structures for the manipulation of a database.

     • These are sometimes called fourth-generation languages.
     • They often include features to help generate forms and display data.

   • Sophisticated users interact with the system without writing programs.
     • They form requests by writing queries in a database query language.
     • These are submitted to a query processor that breaks a DML statement down into instructions for the database manager module.

   • Specialized users are sophisticated users writing special database application programs. These may be CADD systems, knowledge-based and expert systems, complex data systems (audio/video), etc.

   • Naive users are unsophisticated users who interact with the system by using permanent application programs (e.g. automated teller machine).