This chapter provides a reference to the MySQL built-in functions that you can use in your MySQL stored programs. You can use virtually all of the MySQL functions that are available in SQL statements within stored programs, so if you are already familiar with traditional MySQL functions, you can safely skip this chapter. Because this is a reference chapter, we expect you will come back to it from time to time when you need to use a particular functionso don't feel guilty if you decide to skip or only briefly review this chapter.
In general, you can use any of the standard MySQL functions inside stored programs except those functions that work on groups or sets of data. These functionsoften used in combination with the GROUP BY clause in a SQL statementinclude MAX, MIN, COUNT, AVERAGE, and SUM. These functions are not applicable in stored programs (other than in SQL statements embedded in the programs) because stored program variables are scalar (consist of only a single value).
This chapter looks at the built-in functions that we anticipate you might want to use in stored programs; we describe these in the following categories:
MySQL includes a huge number of built-in functions, however, so we can't cover all of them in depth; for a complete list, refer to the online MySQL Reference Manual (http://dev.mysql.com/doc/).