《MysqL学习MysqL笔记之数学函数详解》要点:
本文介绍了MysqL学习MysqL笔记之数学函数详解,希望对您有用。如果有疑问,可以联系我们。
MysqL必读绝对值函数ABS(x)和圆周率函数PI()
MysqL> SELECT ABS(0.5),ABS(-0.5),PI();
+----------+-----------+----------+
| ABS(0.5) | ABS(-0.5) | PI() |
+----------+-----------+----------+
| 0.5 | 0.5 | 3.141593 |
+----------+-----------+----------+
row in set (0.00 sec)
MysqL必读平方根函数SQRT(x)和求余函数MOD(x,y)
MysqL> SELECT SQRT(16),SQRT(3),MOD(13,4);
+----------+--------------------+-----------+
| SQRT(16) | SQRT(3) | MOD(13,4) |
+----------+--------------------+-----------+
| 4 | 1.7320508075688772 | 1 |
+----------+--------------------+-----------+
row in set (0.00 sec)
MysqL必读取整函数CEIL(x)、CEIliNG(x)和FLOOR(x)
MysqL> SELECT CEIL(2.3),CEIL(-2.3),CEIliNG(2.3),CEIliNG(-2.3);
+-----------+------------+--------------+---------------+
| CEIL(2.3) | CEIL(-2.3) | CEIliNG(2.3) | CEIliNG(-2.3) |
+-----------+------------+--------------+---------------+
| 3 | -2 | 3 | -2 |
+-----------+------------+--------------+---------------+
row in set (0.00 sec)
MysqL必读MysqL> SELECT FLOOR(2.3),FLOOR(-2.3);
+------------+-------------+
| FLOOR(2.3) | FLOOR(-2.3) |
+------------+-------------+
| 2 | -3 |
+------------+-------------+
row in set (0.00 sec)
CEIL(x)和CEIliNG(x)返回大于或等于x的最小整数
MysqL必读FLOOR(x)返回小于或等于x的最大整数
MysqL必读随机数函数RAND()和RAND(x)
MysqL> SELECT RAND(),RAND(2),RAND(2);
+--------------------+--------------------+--------------------+
| RAND() | RAND(2) | RAND(2) |
+--------------------+--------------------+--------------------+
| 0.8269294489425881 | 0.6555866465490187 | 0.6555866465490187 |
+--------------------+--------------------+--------------------+
row in set (0.00 sec)
RAND()和RAND(x)这两个函数丢失返回0~1的随机数
MysqL必读区别在于,RAND()返回的数是完全随机的,而RAND(x)在x相同时返回的值相同
MysqL必读四舍五入函数ROUND(x)、ROUND(x,y)和TruncATE(x,y)
MysqL> SELECT ROUND(2.3),ROUND(2.5),ROUND(2.53,1),ROUND(2.55,1);
+------------+------------+---------------+---------------+
| ROUND(2.3) | ROUND(2.5) | ROUND(2.53,1) | ROUND(2.55,1) |
+------------+------------+---------------+---------------+
| 2 | 3 | 2.5 | 2.6 |
+------------+------------+---------------+---------------+
row in set (0.00 sec)
ROUND(x)返回离x最近的整数,也就是对x进行四舍五入处理
MysqL必读ROUND(x,y)返回x保留到小数点后y位的值,在截取时进行四舍五入处理
代码如下:MysqL> SELECT TruncATE(2.53,TruncATE(2.55,1);
+------------------+------------------+
| TruncATE(2.53,1) | TruncATE(2.55,1) |
+------------------+------------------+
| 2.5 | 2.5 |
+------------------+------------------+
row in set (0.00 sec)
TruncATE(x,不进行四舍五入 *** 作
MysqL必读符号函数SIGN(x)
MysqL> SELECT SIGN(-2),SIGN(0),SIGN(2);
+----------+---------+---------+
| SIGN(-2) | SIGN(0) | SIGN(2) |
+----------+---------+---------+
| -1 | 0 | 1 |
+----------+---------+---------+
row in set (0.00 sec)
SIGN(x)返回x的符号,-1为负数,0不变,1为整数
MysqL必读
幂运算函数POW(x,y)、POWER(x,y)
MysqL> SELECT POW(3,2),POWER(3,2);
+----------+------------+
| POW(3,2) | POWER(3,2) |
+----------+------------+
| 9 | 9 |
+----------+------------+
row in set (0.00 sec)
总结
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