MS SQL - 查找和删除重复项

Question

  

可能重复：
  SQL - How can I remove duplicate rows?
  SQL query to delete duplicate rows from same table?

如何在此表中找到双重性？

列 A 是唯一ID，列 E 和 F 无关，所以行1,2,3 和行 4,5 是重复的

Answer 1

我有一个更有效的解决方案：

DELETE FROM MyTable 
    WHERE A NOT IN 
        (SELECT MIN(A) 
         FROM MyTable GROUP BY B, C, D
        );

注意：如果“A”不为NULL，则此方法有效。因此，对于某些类似的任务，它无济于事。

Answer 2

select MyTable.A 
from MyTable 
     join (select B,C,D 
           from MyTable 
           group by B,C,D 
           having Count(*)>1) as T2 on MyTable.B = T2.B 
                                       and MyTable.C = T2.C 
                                       and MyTable.D = T2.D

Answer 3

尝试：

<强> select count(A) Occurrence, B, C, D from TableName group by B, C, D having count(A) > 1

要获取重复列的ID，请使用：

<强> select A from TableName where (B + ' ' + C + ' ' + D) in (select B + ' ' + C + ' ' + D from TableName group by B, C, D having count(A) > 1)

Answer 4

请尝试以下查询：

WITH CustomTable
 AS (SELECT  B, C, D, ROW_NUMBER() OVER (PARTITION BY B, C, D 
                                   ORDER BY ( SELECT 0)) RowNumber
     FROM   TableName)
DELETE FROM CustomTable
WHERE  RowNumber > 1