12.4.1. Arithmetic Operators
The usual arithmetic operators are available. Note that in the
case of -, +, and
*, the result is calculated with
BIGINT (64-bit) precision if both arguments
are integers. If one of the arguments is an unsigned integer,
and the other argument is also an integer, the result is an
unsigned integer. See Section 12.8, “Cast Functions and Operators”.
-
+
Addition:
mysql> SELECT 3+5;
-> 8
-
-
Subtraction:
mysql> SELECT 3-5;
-> -2
-
-
Unary minus. This operator changes the sign of the argument.
mysql> SELECT - 2;
-> -2
Note: If this operator is
used with a BIGINT, the return value is
also a BIGINT. This means that you should
avoid using – on integers that may
have the value of –263.
-
*
Multiplication:
mysql> SELECT 3*5;
-> 15
mysql> SELECT 18014398509481984*18014398509481984.0;
-> 324518553658426726783156020576256.0
mysql> SELECT 18014398509481984*18014398509481984;
-> 0
The result of the last expression is incorrect because the
result of the integer multiplication exceeds the 64-bit
range of BIGINT calculations. (See
Section 11.2, “Numeric Types”.)
-
/
Division:
mysql> SELECT 3/5;
-> 0.60
Division by zero produces a NULL result:
mysql> SELECT 102/(1-1);
-> NULL
A division is calculated with BIGINT
arithmetic only if performed in a context where its result
is converted to an integer.
-
DIV
Integer division. Similar to FLOOR(), but
is safe with BIGINT values.
mysql> SELECT 5 DIV 2;
-> 2
