《Mysql學習MySQL筆記之數(shù)學函數(shù)詳解》要點：
本文介紹了Mysql學習MySQL筆記之數(shù)學函數(shù)詳解，希望對您有用。如果有疑問，可以聯(lián)系我們。
MYSQL必讀絕對值函數(shù)ABS(x)和圓周率函數(shù)PI()
代碼如下:
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必讀平方根函數(shù)SQRT(x)和求余函數(shù)MOD(x,y)
代碼如下:
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必讀取整函數(shù)CEIL(x)、CEILING(x)和FLOOR(x)
代碼如下:
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必讀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的最小整數(shù)
MYSQL必讀FLOOR(x)返回小于或等于x的最大整數(shù)
MYSQL必讀隨機數(shù)函數(shù)RAND()和RAND(x)
代碼如下:
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)這兩個函數(shù)丟失返回0～1的隨機數(shù)
MYSQL必讀區(qū)別在于,RAND()返回的數(shù)是完全隨機的,而RAND(x)在x相同時返回的值相同
MYSQL必讀四舍五入函數(shù)ROUND(x)、ROUND(x,y)和TRUNCATE(x,y)
代碼如下:
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)返回離x最近的整數(shù),也就是對x進行四舍五入處理
MYSQL必讀ROUND(x,y)返回x保留到小數(shù)點后y位的值,在截取時進行四舍五入處理
代碼如下:
mysql> SELECT TRUNCATE(2.53,1), TRUNCATE(2.55,1);
+------------------+------------------+
| TRUNCATE(2.53,1) | TRUNCATE(2.55,1) |
+------------------+------------------+
|????????????? 2.5 |????????????? 2.5 |
+------------------+------------------+
?row in set (0.00 sec)
TRUNCATE(x,y)返回x保留到小數(shù)點后y位的值,不進行四舍五入操作
MYSQL必讀符號函數(shù)SIGN(x)
代碼如下:
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的符號,-1為負數(shù),0不變,1為整數(shù)
MYSQL必讀
冪運算函數(shù)POW(x,y)、POWER(x,y)
代碼如下:
mysql> SELECT POW(3,2), POWER(3,2);
+----------+------------+
| POW(3,2) | POWER(3,2) |
+----------+------------+
|??????? 9 |????????? 9 |
+----------+------------+
?row in set (0.00 sec)
轉(zhuǎn)載請注明本頁網(wǎng)址：
http://www.snjht.com/jiaocheng/3476.html
