Mysql必读MySQL数学函数简明总结

发布时间：2020-12-12 01:31:57 所属栏目：MySql教程来源：网络整理

导读：《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); +--------+---------+--------+ | AB

《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),-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),-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,TRUNCATE(1.99,TRUNCATE(19.99,-1);
+------------------+------------------+------------------+--------------------+
| TRUNCATE(1.33,1) | 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,pow(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,power(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 |
+--------------+--------------------+-----------+-------------------+--------------------+--------------------+-------------------+

（编辑：李大同）

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