MySQL查询从重复的列值中获取最大对应值
让我们首先创建一个表-
mysql> create table DemoTable(ProductName varchar(100),
ProductPrice int
);
使用插入命令在表中插入一些记录-
mysql> insert into DemoTable values('Product-1',56);mysql> insert into DemoTable values('Product-2',78);
mysql> insert into DemoTable values('Product-1',88);
mysql> insert into DemoTable values('Product-2',86);
mysql> insert into DemoTable values('Product-1',45);
mysql> insert into DemoTable values('Product-3',90);
mysql> insert into DemoTable values('Product-2',102);
mysql> insert into DemoTable values('Product-3',59);
使用select语句显示表中的所有记录-
mysql> select *from DemoTable;
这将产生以下输出-
+-------------+--------------+| ProductName | ProductPrice |
+-------------+--------------+
| Product-1 | 56 |
| Product-2 | 78 |
| Product-1 | 88 |
| Product-2 | 86 |
| Product-1 | 45 |
| Product-3 | 90 |
| Product-2 | 102 |
| Product-3 | 59 |
+-------------+--------------+
8 rows in set (0.00 sec)
以下是从重复的列值中获取最大对应值的查询。在这里,我们找到了重复列(例如Product-1,Product-2等)的最大ProductPrice-
mysql> select ProductName,MAX(ProductPrice) from DemoTable group by ProductName;
这将产生以下输出-
+-------------+-------------------+| ProductName | MAX(ProductPrice) |
+-------------+-------------------+
| Product-1 | 88 |
| Product-2 | 102 |
| Product-3 | 90 |
+-------------+-------------------+
3 rows in set (0.00 sec)
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