SQL MIN()函數
SQL MIN函數被用來找出記錄集合中的最小值記錄。
理解MIN函數,可以考慮的employee_tbl表,其具有以下記錄:
SQL> 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)
現在假設基於上述表,想要取daily_typing_pages的最小值,那麼你可以這樣做簡單地使用下面的命令:
SQL> SELECT MIN(daily_typing_pages) -> FROM employee_tbl; +-------------------------+ | MIN(daily_typing_pages) | +-------------------------+ | 100 | +-------------------------+ 1 row in set (0.00 sec)
你可以找出所有使用GROUP BY子句中,每個名稱最小值的記錄如下:
SQL> SELECT id, name, work_date, 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)
您可以使用MIN()函數以及MAX()函數,也可以找出最小值。試試下面的例子:
SQL> 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)