删除多个重复项,在sql中保留最大ID

Question

我有一个包含大量重复量的数据库,每有一个独特的ID,但它们的PermitID和EncID是相同的.我需要删除数据库中除最高ID之外的所有ID.

sql语句,

DELETE FROM tblInvoices 
WHERE EncID = '0237' AND PermitID IN (
SELECT Max(ID) FROM tblInvoices Group BY PermitID)

删除所有记录.我试过了

DELETE FROM tblInvoices 
WHERE EncID = '0237' AND PermitID 
< (SELECT Max(ID) FROM tblInvoices Group BY PermitID)

但我收到错误 Subquery returned more than 1 value. This is not permitted when the subquery follows =, !=, <, <= , >, >= or when the subquery is used as an expression.

数据的一个例子是

ID    PermitID    EncID
1       11          22
2       11          22
3       11          22
4       12          23
5       12          23

我想保留3,删除2和1.我还想保留5并删除4

Answer 1

把事情简单化.

DELETE FROM tblInvoices 
WHERE ID NOT IN
   (SELECT MAX(ID)
   FROM tblInvoices
   GROUP BY EncID, PermitID)