MySQL中的max()函数使用教程

mysql的max()函数是用来找出一个记录集中的最大值记录。

要了解max功能考虑的employee_tbl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)

现在，假设根据上述要取表中daily_typing_pages的最大值值，简单地使用下面的命令：

mysql> select max(daily_typing_pages)
  -> from employee_tbl;
+-------------------------+
| max(daily_typing_pages) |
+-------------------------+
|           350 |
+-------------------------+
1 row in set (0.00 sec)

可以找到所有的记录，最大值为每名使用group by子句如下：

mysql> select id, name, work_date, max(daily_typing_pages)
  -> from employee_tbl group by name;
+------+------+------------+-------------------------+
| id  | name | work_date | max(daily_typing_pages) |
+------+------+------------+-------------------------+
|  3 | jack | 2007-05-06 |           170 |
|  4 | jill | 2007-04-06 |           220 |
|  1 | john | 2007-01-24 |           250 |
|  2 | ram | 2007-05-27 |           220 |
|  5 | zara | 2007-06-06 |           350 |
+------+------+------------+-------------------------+
5 rows in set (0.00 sec)

也可以使用min函数及max功能找到的最低值，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)