Part IV of this book goes beyond the individual components of the PL/SQL language and explains how to build complete PL/SQL applications using program modules.

• Chapter 15, Procedures and Functions , presents the basics of modular programming in PL/SQL using blocks, procedures, functions, and parameters.

• Chapter 16, Packages , describes how to build packages, one of the least understood and least utilized features of PL/SQL.

• Chapter 17, Calling PL/SQL Functions in SQL , describes how you can construct PL/SQL functions and call them from SQL.