Question

我有一个包含这些列的表：

id (pk, int identity), imei (varchar), name (varchar), lastconnected (datetime)

此表中的某些条目具有相同的名称和imei，但不同的ID和不同的最后连接日期。

如何有效过滤掉所有具有重复项的条目（使用SQL脚本），然后删除具有最新lastconnected日期的条目？

Answer 1

简单的ROW_NUMBER和DELETE应该可以解决问题：

WITH CTE AS
(
    SELECT  *,
            RN = ROW_NUMBER() OVER(PARTITION BY imei, [name] ORDER BY lastconnected DESC)
    FROM dbo.YourTable
)
DELETE FROM CTE
WHERE RN = 1;

Answer 2

这很简单，可以解决您的问题

DECLARE @table TABLE
(
 id int, 
 name varchar(10),
 imei varchar(10)
)
insert into @table select 1, 'a','a' 
insert into @table select 2, 'b','a' 
insert into @table select 3, 'c','a' 
insert into @table select 4, 'a','a' 
insert into @table select 5, 'c','a' 
insert into @table select 6, 'a','a' 
insert into @table select 7, 'c','a' 
insert into @table select 8, 'a','a' 

WHILE (exists (select '' from @table group by name , imei having count(*) > 1))  
BEGIN  
 delete from @table where id  in (
 select max(id)  from @table group by imei , name having count(*) > 1)   
End 

select * from @table

Answer 3

我的第一直觉是使用RANK()。如果事情多次重复，这将删除所有重复项，而不仅仅是最新的重复项。

    delete a
    from (
        select id, imei, name, lastconnected, RANK() over(partition by imei, name order by lastconnected) as [rank] from #temp
    ) as a
    where a.rank>1

Answer 4

它为name和iemi的每个组合选择最大日期，然后删除该特定行。

DELETE FROM yourtablee
WHERE (lastconnecteddate,name,imei) in 
                  (SELECT max(lastconnecteddate), name,imei
                     FROM yourtable
                 GROUP BY name,imei)

如何编写删除重复帖子的SQL脚本

4 个答案: