MySQL MAX 函数

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  MAX 函数

  MySQL MAX函数用于在记录集中找出最大值的记录。要了解MAX函数，请考虑一个employee_tbl表，该表具有以下记录-

  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，假设基于上表您要获取daily_typing_pages的最大值，那么您可以使用以下命令简单地做到这一点：

  mysql> SELECT MAX(daily_typing_pages)
     -> FROM employee_tbl;
  +-------------------------+
  | MAX(daily_typing_pages) |
  +-------------------------+
  |           350           |
  +-------------------------+
  1 row in set (0.00 sec)

  您可以使用GROUP BY子句找到每个名称具有最大值的所有记录，如下所示-

  mysql> SELECT id, name, MAX(daily_typing_pages)
     -> FROM employee_tbl GROUP BY name;
  +------+------+-------------------------+
  |  id  | name | MAX(daily_typing_pages) |
  +------+------+-------------------------+
  |   3  | Jack |           170           |
  |   4  | Jill |           220           |
  |   1  | John |           250           |
  |   2  | Ram  |           220           |
  |   5  | Zara |           350           |
  +------+------+-------------------------+
  5 rows in set (0.00 sec)

  您也可以将MIN 函数和MAX 函数一起使用以找出最小值。尝试以下示例-

  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)