sql函数 的 SQL MIN()函数

SQL MIN函数被用来找出记录集合中的最小值记录。

理解MIN函数,可以考虑的employee_tbl表,其具有以下记录:

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)

现在假设基于上述表,想要取daily_typing_pages的最小值,那么你可以这样做简单地使用下面的命令:

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,每个名称最小值的记录如下:

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()函数以及MAX()函数,也可以找出最小值。试试下面的例子:

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)

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