从 GROUP BY 中获取具有最高或最低值的行

Question

在执行GROUP BY 之后，我正在尝试获取具有最高/最低数字的行：

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()

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。

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？

Answer 1

我认为这就是您想要实现的目标：

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

见this SQLFiddle

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

在这里，我使用 minVal 和 Name 自行加入了表格。