MySQL 如何在单个MySQL查询中获取最大值和最小值?

要在单个查询中获取最大值和最小值，请使用聚合函数min()和max()。让我们首先创建一个表：

mysql> create table DemoTable
(
   FirstValue int,
   SecondValue int
);
Query OK, 0 rows affected (0.66 sec)

以下是使用insert命令向表中插入一些记录的查询：

mysql> insert into DemoTable values(10,30);
Query OK, 1 row affected (0.18 sec)
mysql> insert into DemoTable values(30,60);
Query OK, 1 row affected (0.15 sec)
mysql> insert into DemoTable values(100,500);
Query OK, 1 row affected (0.10 sec)
mysql> insert into DemoTable values(50,80);
Query OK, 1 row affected (0.18 sec)

以下是使用select命令从表中显示记录的查询：

mysql> select *from DemoTable;

这将产生以下输出：

+------------+-------------+
| FirstValue | SecondValue |
+------------+-------------+
|         10 |          30 |
|         30 |          60 |
|        100 |         500 |
|         50 |          80 |
+------------+-------------+
4 rows in set (0.00 sec)

以下是在单个查询中获取最大值和最小值的查询：

mysql> select min(FirstValue),min(SecondValue),max(FirstValue),max(SecondValue) from DemoTable;

这将产生以下输出：

+-----------------+------------------+-----------------+------------------+
| min(FirstValue) | min(SecondValue) | max(FirstValue) | max(SecondValue) |
+-----------------+------------------+-----------------+------------------+
|              10 |               30 |             100 |              500 |
+-----------------+------------------+-----------------+------------------+
1 row in set (0.00 sec)

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