MySQL数学函数简明总结(2)-木庄网络博客

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１

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)

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

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 |
+------------+-------------+-------------+--------------+

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

COT(X):　余切函数，函数COT和TAN互为倒函数

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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