从GROUP BY获取具有最高或最低值的行

Question

在执行以下操作后,我正在尝试获取具有最高/最低编号的行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)

要获得最低价值,我会使用 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)

如何根据最低结果获得每个结果的正确ID value？

Answer 1

我认为这是你想要实现的目标:

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 ?
?????????????????????

看到这个SQLFiddle

• 演示更多的价值观
• 具有重复值的演示
• 演示删除重复值(使用DISTINCT)

在这里,我使用minVal和Name自行加入了表格.