《Mysql必读MySQL数学函数简明总结》要点：
本文介绍了Mysql必读MySQL数学函数简明总结，希望对您有用。如果有疑问，可以联系我们。
1. ABS(x): 返回x的绝对值
MYSQL实例
代码如下:
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实例
代码如下:
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实例
代码如下:
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实例
代码如下:
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实例
代码如下:
mysql> select CEIL(-3.35), CEIL(3.35);
+-------------+------------+
| CEIL(-3.35) | CEIL(3.35) |
+-------------+------------+
| -3 | 4 |
+-------------+------------+
6. CEILING(X): 同CEIL(X)
代码如下:
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.
代码如下:
mysql> select FLOOR(-3.35), FLOOR(3.35);
+--------------+-------------+
| FLOOR(-3.35) | FLOOR(3.35) |
+--------------+-------------+
| -4 | 3 |
+--------------+-------------+
8. RAND()和RAND(X)MYSQL实例
RAND(X) 返回一个随机浮点值,范围在０～１之间,X为整数,它被称作种子值,用来产生重复序列.即当Ｘ值相同时,产生的随机数也相同；
MYSQL实例
代码如下:
mysql> select RAND(10), RAND(10), RAND(2), RAND(-2);
+--------------------+--------------------+--------------------+--------------------+
| RAND(10) | RAND(10) | RAND(2) | RAND(-2) |
+--------------------+--------------------+--------------------+--------------------+
| 0.6570515219653505 | 0.6570515219653505 | 0.6555866465490187 | 0.6548542125661431 |
+--------------------+--------------------+--------------------+--------------------+
RAND(): 不带参数的RAND()每次产生不同０～１之间的随机数
代码如下:
mysql> SELECT RAND(), RAND(), RAND();
+--------------------+--------------------+---------------------+
| RAND() | RAND() | RAND() |
+--------------------+--------------------+---------------------+
| 0.6931893636409094 | 0.5147262984092592 | 0.49406343185721285 |
+--------------------+--------------------+---------------------+
9. ROUND(X)和ROUND(X,Y): 四舍五入函数,对Ｘ值按照Ｙ进行四舍五入,Ｙ可以省略,默认值为０;若Ｙ不为０,则保留小数点后面指定Ｙ位.MYSQL实例
代码如下:
mysql> select ROUND(-1.14), ROUND(-1.9), ROUND(1.14), ROUND(1.9);
+--------------+-------------+-------------+------------+
| ROUND(-1.14) | ROUND(-1.9) | ROUND(1.14) | ROUND(1.9) |
+--------------+-------------+-------------+------------+
| -1 | -2 | 1 | 2 |
+--------------+-------------+-------------+------------+
mysql> select ROUND(1.38,1), ROUND(1.38,0), ROUND(232.38,-1), ROUND(232.38,-2);
+---------------+---------------+------------------+------------------+
| ROUND(1.38,1) | ROUND(1.38,0) | ROUND(232.38,-1) | ROUND(232.38,-2) |
+---------------+---------------+------------------+------------------+
| 1.4 | 1 | 230 | 200 |
+---------------+---------------+------------------+------------------+
MYSQL实例
10. TRUNCATE(X,Y): 与ROUND(X,Y)功能类似,但不进行四舍五入,只进行截取.MYSQL实例
代码如下:
mysql> select TRUNCATE(1.33,1), TRUNCATE(1.99,1), TRUNCATE(1.99,0), TRUNCATE(19.99,-1);
+------------------+------------------+------------------+--------------------+
| TRUNCATE(1.33,1) | TRUNCATE(1.99,1) | TRUNCATE(1.99,0) | TRUNCATE(19.99,-1) |
+------------------+------------------+------------------+--------------------+
| 1.3 | 1.9 | 1 | 10 |
+------------------+------------------+------------------+--------------------+
11. SIGN(X): 返回参数Ｘ的符号,Ｘ的值为负、零或正数时返回结果依次为－１,０或１MYSQL实例
代码如下:
mysql> select SIGN(-21), SIGN(-0),SIGN(0), SIGN(0.0), SIGN(21);
+-----------+----------+---------+-----------+----------+
| SIGN(-21) | SIGN(-0) | SIGN(0) | SIGN(0.0) | SIGN(21) |
+-----------+----------+---------+-----------+----------+
| -1 | 0 | 0 | 0 | 1 |
+-----------+----------+---------+-----------+----------+
12. POW(X,Y), POWER(X,Y)和EXP(X)MYSQL实例
POW(X,Y)与POWER(X,Y)功能相同,用于返回Ｘ的Ｙ次乘方的结果值
MYSQL实例
代码如下:
mysql> select pow(2,2), pow(2,-2), pow(-2,2), pow(-2,-2);
+----------+-----------+-----------+------------+
| pow(2,2) | pow(2,-2) | pow(-2,2) | pow(-2,-2) |
+----------+-----------+-----------+------------+
| 4 | 0.25 | 4 | 0.25 |
+----------+-----------+-----------+------------+
mysql> select power(2,2), power(2,-2), power(-2,2), power(-2,-2);
+------------+-------------+-------------+--------------+
| power(2,2) | power(2,-2) | power(-2,2) | power(-2,-2) |
+------------+-------------+-------------+--------------+
| 4 | 0.25 | 4 | 0.25 |
+------------+-------------+-------------+--------------+
MYSQL实例
EXP(X): 返回e的Ｘ乘方后的值:
代码如下:
mysql> select EXP(3), EXP(0), EXP(-3);
+-------------------+--------+---------------------+
| EXP(3) | EXP(0) | EXP(-3) |
+-------------------+--------+---------------------+
| 20.08553692318767 | 1 | 0.04978706836786393 |
+-------------------+--------+---------------------+
13. LOG(X)和LOG10(X): 对数运算函数(Ｘ必须为正数),LOG(X)-返回Ｘ的自然对数(X相对于基数e的对数) LOG10(X)-返回x的基数为10的对数：
代码如下:
mysql> select LOG(-3), LOG(0), LOG(3), LOG10(-100), LOG10(0), LOG10(100);
+---------+--------+--------------------+-------------+----------+------------+
| LOG(-3) | LOG(0) | LOG(3) | LOG10(-100) | LOG10(0) | LOG10(100) |
+---------+--------+--------------------+-------------+----------+------------+
| NULL | NULL | 1.0986122886681098 | NULL | NULL | 2 |
+---------+--------+--------------------+-------------+----------+------------+
14. RADIANS(X) 和 DEGREES(X): 角度与弧度转换函数
代码如下:
mysql> select RADIANS(90), RADIANS(180), DEGREES(PI()), DEGREES(PI()/2);
+--------------------+-------------------+---------------+-----------------+
| RADIANS(90) | RADIANS(180) | DEGREES(PI()) | DEGREES(PI()/2) |
+--------------------+-------------------+---------------+-----------------+
| 1.5707963267948966 | 3.141592653589793 | 180 | 90 |
+--------------------+-------------------+---------------+-----------------+
15. SIN(X), ASIN(X), COS(X), ACOS(X), TAN(X), ATAN(X), COT(X)
SIN(X): 正弦函数,其中Ｘ为弧度值
ASIN(X): 反正弦函数 其中Ｘ必须在－１到１之间
COS(X): 余弦函数,其中Ｘ为弧度值
ACOS(X): 反余弦函数 其中Ｘ必须在－１到１之间
TAN(X): 正切函数,其中Ｘ为弧度值
ATAN(X): 反正切函数,ATAN(X)与TAN(X)互为反函数MYSQL实例
COT(X): 余切函数,函数COT和TAN互为倒函数
MYSQL实例
代码如下:
mysql> select SIGN(PI()/2),ASIN(1),COS(PI()), ACOS(-1), TAN(PI()/4), ATAN(1), COT(0.5);
+--------------+--------------------+-----------+-------------------+--------------------+--------------------+-------------------+
| SIGN(PI()/2) | ASIN(1) | COS(PI()) | ACOS(-1) | TAN(PI()/4) | ATAN(1) | COT(0.5) |
+--------------+--------------------+-----------+-------------------+--------------------+--------------------+-------------------+
| 1 | 1.5707963267948966 | -1 | 3.141592653589793 | 0.9999999999999999 | 0.7853981633974483 | 1.830487721712452 |
+--------------+--------------------+-----------+-------------------+--------------------+--------------------+-------------------+
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