[Solved] Can some expert please explain what this query is doing? [duplicate]
ROW_NUMBER in a subquery combined with a filter on it in the outer query is an idiom to filter out all but the first row in a group. So here ROW_NUMBER() OVER(PARTITION BY [dbo].[RegistrationHistory].[SerialNumber]) Assigns the row with the lowest SerialNumber 1, the next lowest, 2, etc. Then later where t.seq = 1 removes all … Read more