Question

我有下表 - mytable：

----id----|----user_id----|----value-----|
----1-------------1------------- 9
----2-------------1------------- 8
----3-------------2 -------------11
----4-------------2-------------12
----5-------------3-------------11
----6-------------4-------------8
----7-------------1-------------3

我想SELECT * FROM mytable...其中value有一条记录如下：

----id----|----user_id----|----value-----
----1-------------1-------------9
----4-------------2-------------12
----7-------------1-------------3

请注意，值8和值11有重复项，我删除了所有

Answer 1

试试这个

SELECT * FROM mytable
GROUP BY `value`
HAVING count(*) = 1

或

SELECT * FROM mytable
GROUP BY `value`
HAVING count(*) < 2

Answer 2

您可以尝试左连接：

SELECT T1.id, T1.user_id, T1.value
FROM yourtable T1
LEFT JOIN yourtable T2
ON T1.value = T2.value
AND T1.id <> T2.id
WHERE T2.id IS NULL

Answer 3

以下查询应该适用于上面提到的问题..

SELECT T1。* 从MYTABLE T1，（选择价值来自MYTABLE 按价值分组有COUNT（*）= 1 ）T2 在哪里T1.VALUE = T2.VALUE;

此致 Venk

Answer 4

我会这样做：

select t1.* 
from table1 t1
where 1 = (select count(t2.id)
                    from table1 t2
                    where t1.value = t2.value 
                    )

希望它有效。

PS：id必须是唯一的密钥。

mysql选择唯一的行

4 个答案: