查询结果没有反转

Question

我有桌子： 用户A， 用户B， numberOfConnections

我想写一个查询，它只返回没有反向意义的行或示例： 对于数据：

1 2 10
1 3 10
1 5 10
1 6 10
2 6 10
2 5 10
5 1 10
5 2 10
3 1 10

它应该返回

1 2 10
1 3 10
1 5 10
1 6 10
2 6 10
2 5 10

行：

5 1 10
5 2 10
3 1 10

无效，因为已经有相应的

1 5 10
2 5 10
3 1 10

感谢您的帮助 再见

Answer 1

这将做你想要的事情

SELECT mt1.UserA, mt1.UserB, mt1.numberOfConnections
FROM MyTable mt1
LEFT OUTER JOIN MyTable mt2 ON mt1.UserA = mt2.UserB
        AND mt1.UserB = mt2.UserA
WHERE mt2.UserA IS NULL
    OR mt1.UserA < mt2.UserA

Answer 2

为什么不添加UserA＆lt; UserB在where子句中。 ？

Answer 3

with t1 as (
select col1 ,col2,
     row_number() 
      over(partition by case when col1>col2 then col1+col2 else col2+col1 end 
           order by case when col1>col2 then col1+col2 else col2+col1 end) as rownum 
from table_1 )

select * from t1 where rownum =1

如果您的数据类型col1和col2不是varchar，只需cast他们

您可以将row_number替换为group by

Answer 4

使用更新

A-结果无反向

Select UserA, UserB, numberOfConnections
From TName
Where ID Not IN(
SELECT t1.ID
FROM TName As t1 INNER JOIN TName As t2 ON (t1.UserA = t2.UserB) AND (t1.UserB = t2.UserA))

B-结果反向仅重复

Select UserA, UserB, numberOfConnections
From TName
Where ID IN(
SELECT t1.ID
FROM TName As t1 INNER JOIN TName As t2 ON (t1.UserA = t2.UserB) AND (t1.UserB = t2.UserA))

C-结果仅反转不重复

Select UserA, UserB, numberOfConnections
From TName
Where ID IN(
SELECT t1.ID
FROM TName As t1 INNER JOIN TName As t2 ON (t1.UserA = t2.UserB) AND (t1.UserB = t2.UserA) and (t1.UserA<t1.UserB))

D-结果无反向且不重复反向

一个 联盟 ç