[Solved] DELETE duplicate values in SQL

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I’ll take a stab at your problem. This is only a guess, based on the query you provided. A complete question would have described what exactly you mean by a duplicate row.

delete from Registrations
where exists (
    select 1
    from Registrations r2
    where   r2.UserItemId = Registrations.UserItemId
        and r2.CourseOfferingId = Registrations.CourseOfferingId
        and r2.Id < Registrations.Id
);

Apparently you have multiple rows that have the same UserItemId and CourseOffereningId but different Id values. I’m presuming that you want to keep the one with the lowest Id and discard the others.

The subquery in the query takes each row in the table and checks to see if there’s another row like it but with a lower Id. If the answer if yes then the row is deleted.

solved DELETE duplicate values in SQL