The introductory chapters in this book (Chapters 1–4) provide an overview of SQL, SQL built-in functions, UDFs, and major vendor implementations of RDBMS and SQL functions. These chapters are meant to serve as an introduction to SQL function architecture and concepts for those readers who need to increase their knowledge and sharpen their skills. | Programmer to Programmer 5 SQL Functions Programmer s Reference Arie Jones Ryan K. Stephens Ronald R. Plew Robert F. Garrett Alex Kriegel Updates source code and Wrox technical support at SQL Functions Programmer s .