Question

select T1.C1
      ,T1.C2
      ,T2.C2
from table1 T1
    join table2 T2
      on T1.C1 = T2.C1
     and T1.C2 != T2.C2
     and T2.C1 != ''

输出：

| T1.C1 | T1.C2 | T2.C2  |
--------------------------
| 1     | A1    | B14    |
| 1     | B14   | A1     | 
| 2     | A3    | B14    |  
| 2     | B14   | A3     |

简单SQL查询返回两个不同项目中的所有C1。如何从查询中删除所有重复项以获得此结果：

| T1.C1 | T1.C2 | T2.C2  |
--------------------------
| 1     | A1    | B14    |
| 2     | A3    | B14    |

Answer 1

而不是：

T1.C2 != T2.C2

使用：

T1.C2 <= T2.C2

只要每个(T1.C2 < T2.C2)对都存在等效的(T1.C2 > T2.C2)对，就像您的示例数据一样，例如， (A1, B14)对(B14, A1)也存在。

否则，您可以使用：

SELECT T1.C1, T1.C2, T2.C2
FROM (
   SELECT T1.C1, T1.C2, T2.C2,
          ROW_NUMBER() OVER (PARTITION BY T1.C1,
                                          IIF(T1.C2 <= T2.C2, T1.C2, T2.C2),
                                          IIF(T1.C2 <= T2.C2, T2.C2, T1.C2)
                             ORDER BY T1.C2, T2.C2) AS rn                          
   FROM  table1 T1
   JOIN table2 T2
      ON T1.C1 = T2.C1
         AND T1.C2 != T2.C2
         AND T2.C1 != '') AS t
WHERE t.rn = 1

Answer 2

如果我理解了你之后的内容，下面是生成此输出的代码：

T1xC2                hits
-------------------- -------------------
A1                   A3,B14
A3                   A1,B14
B14                  A1,A3

由以下人员制作：

Declare @T1 Table (C1 int, C2 varchar(20))
Declare @T2 Table (C1 int, C2 varchar(20))

insert into @T1
Select 1, 'A1'
union select 1, 'B14'
union select 2, 'A3'
union select 2, 'B14'

Insert into @T2
Select  1, 'B14'
Union Select 1, 'A1'
union select 2, 'B14'
union select 2, 'A3'

;WITH mix
AS (
     SELECT T1.C1 AS [T1xC1]
          ,T2.C1 AS [T2xC1]
          ,T1.C2 AS [T1xC2]
          ,T2.C2 AS [T2xC2]
          ,ROW_NUMBER() OVER (
               ORDER BY (
                         SELECT NULL
                         )
               ) AS rnk
     FROM @T1 T1
     CROSS JOIN @t2 T2
     )
     ,Groupwork
AS (
     SELECT *
     FROM mix m
     WHERE EXISTS (
               SELECT 1
               FROM Mix m2
               WHERE m.T1xC2 = m2.T1xC2
                    AND m.T2xC2 <> m2.T2xC2
                    AND m.T1xC2 <> m.t2xc2
               )
     )
     ,GroupRows
AS (
     SELECT DISTINCT T1xc1, T1xC2
     FROM Groupwork
     )
SELECT distinct T1xC2, x.hits
FROM GroupRows g
CROSS APPLY (
     SELECT STUFF((
                    SELECT distinct ',' + g2.T2xC2
                    FROM Groupwork g2
                    WHERE g2.T1xC2 = g.T1xC2
                    FOR XML PATH('')
                    ), 1, 1, '') hits
     ) x

删除sql select duplicates

2 个答案: