在写这篇文章之前,xxx已经写过了几篇关于改返回函数主题的文章,想要了解的朋友可以去翻一下之前的文章
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 |
+----------+-----------+----------+
1 row in set (0.00 sec)
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 |
+----------+--------------------+-----------+
1 row in set (0.00 sec)
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 |
+-----------+------------+--------------+---------------+
1 row in set (0.00 sec)
mysql> SELECT FLOOR(2.3), FLOOR(-2.3);
+------------+-------------+
| FLOOR(2.3) | FLOOR(-2.3) |
+------------+-------------+
| 2 | -3 |
+------------+-------------+
1 row in set (0.00 sec)
CEIL(x)和CEILING(x)返回大于或于等x的最小数整
FLOOR(x)返回小于或于等x的最大数整
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 |
+--------------------+--------------------+--------------------+
1 row in set (0.00 sec)
每日一道理
自己把自己说服了,是一种理智的胜利;自己被自己感动了,是一种心灵的升华;自己把自己征服了,是一种人生的成功。
RAND()和RAND(x)这两个函数失丢返回0~1的随机数
区分在于,RAND()返回的数是完整随机的,而RAND(x)在x同相时返回的值同相
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 |
+------------+------------+---------------+---------------+
1 row in set (0.00 sec)
ROUND(x)返回离x近最的数整,也就是对x停止四舍五入处置
ROUND(x,y)返回x留保到小数点后y位的值,在截取时停止四舍五入处置
mysql> SELECT TRUNCATE(2.53,1), TRUNCATE(2.55,1);
+------------------+------------------+
| TRUNCATE(2.53,1) | TRUNCATE(2.55,1) |
+------------------+------------------+
| 2.5 | 2.5 |
+------------------+------------------+
1 row in set (0.00 sec)
TRUNCATE(x,y)返回x留保到小数点后y位的值,不停止四舍五入操纵
符号函数SIGN(x)
mysql> SELECT SIGN(-2), SIGN(0), SIGN(2);
+----------+---------+---------+
| SIGN(-2) | SIGN(0) | SIGN(2) |
+----------+---------+---------+
| -1 | 0 | 1 |
+----------+---------+---------+
1 row in set (0.00 sec)
SIGN(x)返回x的符号,-1为正数,0变不,1为数整
幂算运函数POW(x,y)、POWER(x,y)
mysql> SELECT POW(3,2), POWER(3,2);
+----------+------------+
| POW(3,2) | POWER(3,2) |
+----------+------------+
| 9 | 9 |
+----------+------------+
1 row in set (0.00 sec)
文章结束给大家分享下程序员的一些笑话语录: 祝大家在以后的日子里. 男生象Oracle般健壮; 女生象win7般漂亮; 桃花运象IE中毒般频繁; 钱包如Gmail容量般壮大, 升职速度赶上微软打补丁 , 追女朋友像木马一样猖獗, 生活像重装电脑后一样幸福, 写程序敲代码和聊天一样有**。