sql - 删除不基于主键的重复行

Question

我的数据库中有这张表：

tblAgencies
----------------------
AgencyID (PK)
VendorID
RegionID
Name
Zip

长话短说，我不小心将我的整个表格复制到了自身中——所以我表格中的每一行都有一个副本。

但是由于我的AgencyID字段是身份并自动递增，我需要根据所有其他字段查找重复项，因为AgencyID它是唯一的。

有谁知道我该怎么做？

Answer 1

这将保留最旧的 AgencyID 值，否则将删除任何重复项。

;WITH x AS 
(
  SELECT *, rn = ROW_NUMBER() OVER 
    (PARTITION BY VendorID, RegionID, Name, Zip
    ORDER BY AgencyID) FROM dbo.tblAgencies
)
DELETE x WHERE rn > 1;

不过要小心；如果其他表引用 AgencyID并且它们已经获得了您的任何更新的错误值，这可能不起作用。

Answer 2

最简单的解决方案，使用 select distinct 进入临时表，然后重新加载原始

Answer 3

;with CTE 
AS
(SELECT MAX(AgencyID) AgentID,VendorID ,
RegionID ,
Name ,
Zip  FROM tblAgencies
GROUP BY VendorID ,
RegionID ,
Name ,
Zip 
HAVING COUNT(*) > 1)

DELETE FROM tblAgencies WHERE  EXISTS  (SELECT 1 FROM CTE
WHERE  AgentID = tblAgencies.AgencyID)

Answer 4

也许这会有所帮助：如何在存在主键的情况下删除重复项？

Answer 5

很多答案会给你你想要的，但没有必要使用 CTE 或做任何分组，最简单的方法就是：

delete   t1
from     tblAgencies t1
join     tblAgencies t2
on       t1.VendorId = t2.VendorId
and      t1.RegionId = t2.RegionId
and      t1.Name = t2.Name
and      t1.Zip = t2.Zip
and      t1.AgencyId > t2.AgencyId

Answer 6

如果所有其他列的组合是唯一的，则此查询将为您提供重复项：

select * from mytable t1
where exists
         (select * from mytable t2 
         where t1.VendorID = t2.VendorID 
         and t1.RegionID = t2.RegionID 
         and and t1.Name = t2.Name 
         and t1.Zip = t2.Zip 
         and t1.AgencyID > t2.AgencyID)

Answer 7

这应该为您提供所有具有重复值的行，除了最小的机构 ID 行。

select *
  from tblAgencies
  where AgencyID not in (select min(AgencyID)
                           from tblAgencies
                           group by VendorID, RegionID, Name, Zip)

编辑：添加SQLFiddle

Answer 8

;with CTE 
AS
 (
   SELECT ID_Column, rn = ROW_NUMBER() OVER (PARTITION BY Column1, Column2, Column3... ORDER BY ID ASC)
  FROM T
)
DELETE FROM CTE 
WHERE rn >= 2