从GROUP BY获取最高或最低值的行 [英] Get row with highest or lowest value from a GROUP BY

问题描述

我试图在执行 GROUP BY 后获得最高/最低编号的行：

I'm trying to get the row with the highest/lowest number, after performing a GROUP BY:

这是我的测试数据

mysql> SELECT * FROM test;
+----+-------+------+
| id | value | name |
+----+-------+------+
|  1 |    10 | row1 |
|  2 |    12 | row2 |
|  3 |    10 | row2 |
|  4 |     5 | row2 |
+----+-------+------+
4 rows in set (0.00 sec)

为了得到最小值，我将使用 MIN（）

To get the lowest value, I'll use MIN()

mysql> SELECT id, name, MIN(value) AS value FROM test GROUP BY name;
+----+------+-------+
| id | name | value |
+----+------+-------+
|  1 | row1 |    10 |
|  2 | row2 |     5 |
+----+------+-------+
2 rows in set (0.00 sec)

现在，id row2 是 2 ，但它应该是 4 。

Now, the id row2 is 2, but it should be 4.

我也尝试了一个连接：

I also tried with a join:

mysql> SELECT t1.* FROM 
       (SELECT id, name, MIN(value) AS value 
          FROM test GROUP BY name) AS t1 
       INNER JOIN test AS t2 ON t1.id = t2.id;
+----+------+-------+
| id | name | value |
+----+------+-------+
|  1 | row1 |    10 |
|  2 | row2 |     5 |
+----+------+-------+
2 rows in set (0.00 sec)

如何根据最低值的结果得到每个结果的正确ID？

How can I get the correct ID for each result based on what the lowest value is?

推荐答案

我认为这就是您要实现的目标：

I think this is what you are trying to achieve:

SELECT t.* FROM test t
JOIN 
( SELECT Name, MIN(Value) minVal
  FROM test GROUP BY Name
) t2
ON t.Value = t2.minVal AND t.Name = t2.Name;

输出：

╔════╦═══════╦══════╗
║ ID ║ VALUE ║ NAME ║
╠════╬═══════╬══════╣
║  1 ║    10 ║ row1 ║
║  4 ║     5 ║ row2 ║
╚════╩═══════╩══════╝

请参阅 this SQLFiddle

• 具有更多价值的演示


• 具有重复值的演示


• 删除重复值的演示（使用 DISTINCT ）



See this SQLFiddle

• Demo with more values
• Demo with duplicate values
• Demo with removing duplicate values (using DISTINCT)

这里我用minVal和Name自加入表。

Here I have self-joined the table with minVal and Name.

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