Question

我有一对多的桌子已经变得有点乱，我正在寻找更新架构以防止将来发生这种情况。首先，我需要清理现有数据以用作合并脚本的源。不知道如何判断这种类型的查询对谷歌的影响并没有真正帮助。

简单地说，这就是我所看到的以及我想要提取的东西。

DECLARE @TestTable
TABLE ([IdA] INT, [IdB] INT);

DECLARE @Expected
TABLE ([KeyId] INT, [MemberId] INT);

INSERT INTO @TestTable
VALUES
    (1, 2),
    (2, 1),
    (1, 3),
    (4, 1),
    (12, 4),

    (5, 6),
    (6, 7),

    (8, 9),

    (11, 10)

INSERT INTO @Expected
VALUES
    (1, 1),
    (1, 2),
    (1, 3),
    (1, 4),
    (1, 12),

    (5, 5),
    (5, 6),
    (5, 7),

    (8, 8),
    (8, 9),

    (10, 10),
    (10, 11)

组的最低ID应被视为关键
群组成员数量始终少于20
只要结果数据集正确，订购就不重要

非常感谢。

Answer 1

这是实现您想要做的事情的一种方式：

这是SQLFiddle

--Let's copy the rows in as they are to begin with
INSERT INTO 
  @Expected
SELECT
   [IdA]
  ,[IdB]
FROM 
  @TestTable


--Lets switch the column values where the higher ID's are in column B  
UPDATE @Expected
SET [KeyId] = [MemberId], [MemberId] = [KeyId]  
WHERE [KeyId] > [MemberId]

--Now lets set the KEY IDs
UPDATE
  E
SET
  E.[KeyId] = E1.[KeyId]
FROM
  @Expected E
INNER JOIN
  @Expected E1 
ON
  E1.[MemberId] = E.[KeyId]

--and you wanted mappings for the keys to themselves in your result set, so let's add those
INSERT INTO
  @Expected
SELECT
  [KeyId]
 ,[KeyId]
FROM
  @Expected E 
WHERE NOT EXISTS
  (SELECT * FROM @Expected WHERE [KeyId] = E.[KeyId] AND [MemberId] = [KeyID])

SELECT DISTINCT 
  * 
FROM 
  @Expected

请注意，我最后选择了DISTINCT，因为我没有从结果集中删除重复项。

多次清理

1 个答案: