Most of the emphasis in this book has been on ways of using SQL and RDBMS. Using functions written in SQL and other languages greatly extends the capabilities of existing RDBMS for handling molecular structures. Because the RDBMS is run as a server, a client program is necessary to interact with the RDBMS. Chapter 5 introduced several common client programs to do this. When developing a more complex system, existing applications may not satisfy the needs of the project. In that case, it becomes necessary to develop new client programs to interact with the RDBMS.

This chapter discusses ways in which more complex client applications can be written. These programs use SQL to select, insert, delete or update table in the database.