MySQL Min()函数

发布于 2015-07-31 16:36:11 | 233 次阅读 | 评论: 0 | 来源: 网络整理

MySQL的Min()函数用来找出记录集的最小值纪录。

理解Min()函数，考虑一个employee_tbl表，它是具有以下记录：

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)

现在假设根据上表中,想获取daily_typing_pages的最小值，那么可以简单地使用下面的命令：

mysql> SELECT MIN(daily_typing_pages)
    -> FROM employee_tbl;
+-------------------------+
| MIN(daily_typing_pages) |
+-------------------------+
|                     100 |
+-------------------------+
1 row in set (0.00 sec)

使用GROUP BY子句找到所有每个名称最小值的记录如下：

mysql>SELECT id, name, MIN(daily_typing_pages)
    -> FROM employee_tbl GROUP BY name;
+------+------+-------------------------+
| id   | name | MIN(daily_typing_pages) |
+------+------+-------------------------+
|    3 | Jack |                     100 |
|    4 | Jill |                     220 |
|    1 | John |                     250 |
|    2 | Ram  |                     220 |
|    5 | Zara |                     300 |
+------+------+-------------------------+
5 rows in set (0.00 sec)

可以使用Min()函数和Max()函数一起，找出最小值和最大值。试试下面的例子：

mysql> SELECT MIN(daily_typing_pages) least, MAX(daily_typing_pages) max
    -> FROM employee_tbl;
+-------+------+
| least | max  |
+-------+------+
|   100 |  350 |
+-------+------+
1 row in set (0.01 sec)