Delete duplicated records from two databases

Question

I manage to identify duplicate records from two different databases:

select * from 
    taskperformance a,  taskperformance@dm_prod b
where 
    a.activityin = b.activityin
    and a.completiondate = b.completiondate

How can I delete duplicated records from b?

I tried:

delete taskperformance@dm_prod  where exist ( 
select * from 
    taskperformance a,  taskperformance@dm_prod b
where 
    a.activityin = b.activityin
    and a.completiondate = b.completiondate )

But delete more that I need.

Answer 1

Yeah - you shouldn't re-reference b in the subquery:

delete taskperformance@dm_prod b
where exists (
    select * from taskperformance a
    where a.activityin = b.activityin 
    and a.completiondate = b.completiondate 
)