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详解MySQL中的SQRT函数的使用方法_MySQL

WBOY
WBOYOriginal
2016-06-01 13:00:311626browse

MySQL的SQRT函数是用来计算出任何数量的平方根。可以使用SELECT语句找出方检定根的任意数如下:

mysql> select SQRT(16);
+----------+
| SQRT(16) |
+----------+
| 4.000000 |
+----------+
1 row in set (0.00 sec)

所看到的浮点值,因为内部MySQL将处理浮点数据类型的平方根。

可以使用SQRT函数,计算出记录的平方根。了解SQRT函数更详细用法,考虑EMPLOYEE_TBL的表具有以下记录:

mysql> SELECT * FROM employee_tbl;
+------+------+------------+--------------------+
| id  | name | work_date | daily_typing_pages |
+------+------+------------+--------------------+
|  1 | John | 2007-01-24 |        250 |
|  2 | Ram | 2007-05-27 |        220 |
|  3 | Jack | 2007-05-06 |        170 |
|  3 | Jack | 2007-04-06 |        100 |
|  4 | Jill | 2007-04-06 |        220 |
|  5 | Zara | 2007-06-06 |        300 |
|  5 | Zara | 2007-02-06 |        350 |
+------+------+------------+--------------------+
7 rows in set (0.00 sec)

假设根据上面的表格,要计算所有的dialy_typing_pages的平方根,然后可以通过使用下面的命令:

mysql> SELECT name, SQRT(daily_typing_pages)
  -> FROM employee_tbl;
+------+--------------------------+
| name | SQRT(daily_typing_pages) |
+------+--------------------------+
| John |        15.811388 |
| Ram |        14.832397 |
| Jack |        13.038405 |
| Jack |        10.000000 |
| Jill |        14.832397 |
| Zara |        17.320508 |
| Zara |        18.708287 |
+------+--------------------------+
7 rows in set (0.00 sec)


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