Question

我找到了Jeff Smith的解决方案，它显示了两个表之间的差异：

SELECT MIN(TableName) as TableName, ID, COL1, COL2, COL3 ...
FROM
(
  SELECT 'Table A' as TableName, A.ID, A.COL1, A.COL2, A.COL3, ...
  FROM A
  UNION ALL
  SELECT 'Table B' as TableName, B.ID, B.COL1, B.COl2, B.COL3, ...
  FROM B
) tmp
GROUP BY ID, COL1, COL2, COL3 ...
HAVING COUNT(*) = 1
ORDER BY ID

在我的项目中，我需要比较一下。仅限col1和col2，rest用于其他操作。我试着用

HAVING (COUNT(col1) = 1 and COUNT(col2) = 1)

但没有效果。

你能否请我解决这个问题？

Answer 1

使用以下COL1获取COL2中A和B的{{1}}值

SELECT COL1, COL2 FROM A
EXCEPT
SELECT COL1, COL2 FROM B

将结果用作派生表，将它们连接回A并获取所有列：

SELECT 'A' AS SRC, A.COL1, A.COL2, A.COL3...
FROM (
  SELECT COL1, COL2 FROM A
  EXCEPT
  SELECT COL1, COL2 FROM B
) AS diff
INNER JOIN A ON diff.COL1 = A.COL1 AND diff.COL2 = A.COL2

同样，使用EXCEPT获取仅存在于COL1中的COL2和B的值，并将结果集合加入B以获取完整的行相应

将两组与UNION ALL结合使用：

SELECT 'A' AS SRC, A.COL1, A.COL2, A.COL3...
FROM (
  SELECT COL1, COL2 FROM A
  EXCEPT
  SELECT COL1, COL2 FROM B
) AS diff
INNER JOIN A ON diff.COL1 = A.COL1 AND diff.COL2 = A.COL2

UNION ALL

SELECT 'B' AS SRC, B.COL1, B.COL2, B.COL3...
FROM (
  SELECT COL1, COL2 FROM B
  EXCEPT
  SELECT COL1, COL2 FROM A
) AS diff
INNER JOIN B ON diff.COL1 = B.COL1 AND diff.COL2 = B.COL2
;

Answer 2

您正在从错误的位置删除列。您应该从列列表中删除它，而不是从列中删除它：

SELECT MIN(TableName) as TableName, ID, COL1, COL2
FROM
(
  SELECT 'Table A' as TableName, A.ID, A.COL1, A.COL2
  FROM A
  UNION ALL
  SELECT 'Table B' as TableName, B.ID, B.COL1, B.COl2
  FROM B
) tmp
GROUP BY ID, COL1, COL2
HAVING COUNT(*) = 1
ORDER BY ID

要保留结果中的其他列，您可以使用MIN（或朋友）来保留它们：

SELECT MIN(TableName) as TableName, ID, COL1, COL2, MIN(COL3), MIN(COL4), ...
FROM
(
  SELECT 'Table A' as TableName, A.ID, A.COL1, A.COL2, A.COL3, A.COL4, ...
  FROM A
  UNION ALL
  SELECT 'Table B' as TableName, B.ID, B.COL1, B.COL2, B.COL3, B.COL4, ...
  FROM B
) tmp
GROUP BY ID, COL1, COL2
HAVING COUNT(*) = 1
ORDER BY ID

请注意，这在某些情况下效果不佳。如果两个表中的两行相同（包括ID），那么即使它不是，它也会发现它有差异。此外，在此版本中，如果您有多个行COL1和COL2相同，那么这也不行。我会将这两张表加在一起，以便进行更有力的比较。

T-SQL找到差异

2 个答案: