function

Constant is a name of simple value (number, text), which should not change during code execution. Constants are case sensitive, and good programming style requires use them in uppercase. Besides large number of constants coming from php engine, there are “magic” constants which value depends on where they are requested.

This time, I will make a closer look at mysql user variables. They can be divided into two main categories: defined variables, used in procedures and functions and undefined, also can be used in procedures and function, but also can be used in sql queries as in-line code.