MySQL数学函数简明总结

1. ABS(x): 返回x的绝对值

mysql> select ABS(1), ABS(-1), ABS(0);
+--------+---------+--------+
| ABS(1) | ABS(-1) | ABS(0) |
+--------+---------+--------+
|      1 |       1 |      0 |
+--------+---------+--------+

2. PI(): 返回圆周率

mysql> select PI();
+----------+
| PI()     |
+----------+
| 3.141593 |
+----------+

3. SQRT(x): 返回x的平方根，要求（x为非负数，返回NULL）

mysql> select SQRT(49), SQRT(0), SQRT(-49);
+----------+---------+-----------+
| SQRT(49) | SQRT(0) | SQRT(-49) |
+----------+---------+-----------+
|        7 |       0 |      NULL |
+----------+---------+-----------+

4. MOD(x,y): 求余函数，返回x被y除后的余数；对于带有小数部分的数据值也起作用，它返回除法运算后的精确余数。

mysql> select MOD(31,8), MOD(21,-8), MOD(-7,2), MOD(-7,-2), MOD(45.5,6);
+-----------+------------+-----------+------------+-------------+
| MOD(31,8) | MOD(21,-8) | MOD(-7,2) | MOD(-7,-2) | MOD(45.5,6) |
+-----------+------------+-----------+------------+-------------+
|         7 |          5 |        -1 |         -1 |         3.5 |
+-----------+------------+-----------+------------+-------------+

5. CEIL(X): 返回不小X的最小整数值，返回值转为一个BIGINT.

mysql> select CEIL(-3.35), CEIL(3.35);
+-------------+------------+
| CEIL(-3.35) | CEIL(3.35) |
+-------------+------------+
|          -3 |          4 |
+-------------+------------+

6. CEILING(X): 同CEIL(X)

mysql> select CEILING(-3.35), CEILING(3.35);
+----------------+---------------+
| CEILING(-3.35) | CEILING(3.35) |
+----------------+---------------+
|             -3 |             4 |
+----------------+---------------+

7. FLOOR(X):返回不大于X的最大整数值，返回值转为一个BIGINT.