在 MySQL 中从具有相应重复列值的列中选择最小行值
mysqlmysqli database更新于 2024/1/9 16:03:00
首先我们创建一个表 −
mysql> create table DemoTable1875 ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, Class varchar(20), Amount int ); Query OK, 0 rows affected (0.00 sec)
使用 insert 命令在表中插入一些记录 −
mysql> insert into DemoTable1875(Class,Amount) values('X',750);
Query OK, 1 row affected (0.00 sec)
mysql> insert into DemoTable1875(Class,Amount) values('X',140);
Query OK, 1 row affected (0.00 sec)
mysql> insert into DemoTable1875(Class,Amount) values('X',450);
Query OK, 1 row affected (0.00 sec)
mysql> insert into DemoTable1875(Class,Amount) values('Y',6780);
Query OK, 1 row affected (0.00 sec)
mysql> insert into DemoTable1875(Class,Amount) values('Z',1350);
Query OK, 1 row affected (0.00 sec)
mysql> insert into DemoTable1875(Class,Amount) values('Z',2050);
Query OK, 1 row affected (0.00 sec)
使用 select 语句显示表中的所有记录 −
mysql> select * from DemoTable1875;
这将产生以下输出 −
+----+-------+--------+ | Id | Class | Amount | +----+-------+--------+ | 1 | X | 750 | | 2 | X | 140 | | 3 | X | 450 | | 4 | Y | 6780 | | 5 | Z | 1350 | | 6 | Z | 2050 | +----+-------+--------+ 6 rows in set (0.00 sec)
以下是选择行的查询
mysql> select Class,Min(Amount) from DemoTable1875 group by Class;
这将产生以下输出 −
+-------+-------------+ | Class | Min(Amount) | +-------+-------------+ | X | 140 | | Y | 6780 | | Z | 1350 | +-------+-------------+ 3 rows in set (0.00 sec)
