This guide aims to help the reader understand Informix stored procedures, which can be used to improve the performance of SQL code, tighten security, reduce maintenance of permissions and maximize data integrity. The structure, program logic flow and control of stored procedures, as used in the Informix Stored Procedure Language (SPL) - Informix' version of middleware is included. Examples which show how to design and apply stored procedures of the right size and scope are also documented in the text. The author shows how stored procedures can be used to optimize code while improving security and data integrity. A comprehensive SPL syntax reference is included, as are more than 20 stored procedures that can be used or adapted by the reader.