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

问题描述

在执行 GROUP BY 后，我正在尝试获取具有最高/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)

要获得最低值，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.

我也尝试过加入:

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)

如何根据最低的 value 为每个结果获取正确的 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:

<头>

ID	VALUE	姓名
1	10	row1
4	5	row2

参见这个SQLFiddle

• 具有更多价值的演示
• 带有重复值的演示
• 删除重复值的演示(使用DISTINCT)

这里我用 minVal 和 Name 自行加入了表.

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

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