MySQL in a Nutshell

Appendix B. Operators

Operators are used in mathematical or logical operations. An operator is typically placed between two values (i.e., numbers, strings, columns, or expressions) for comparing or evaluating them. There are four types of operators: arithmetic, relational, logical, and bitwise. This appendix provides a listing of operators grouped by these four types.

Arithmetic Operators

The arithmetic operators in MySQL work only on numbers, and not on strings. However, MySQL will convert a string as a number when in a numeric context if it can. If it can't convert a particular string, it will convert it to 0. The arithmetic operators allowed are listed in Table B-1.

Table B-1. Arithmetic operators

Operator	Use
+	Addition
-	Subtraction and negation
*	Multiplication
/	Division
DIV	Division of integers
%	Modulo division

The minus sign may be used for subtracting numbers or for setting a number to a negative. The DIV operator converts values to integers and returns only integers. It doesn't round fractions that would be returned, but truncates them.