如何根据每组的条件过滤记录

Question

In SQL how can I express this question: For all groups, return all records in a group that match the result of a condition specific to the group.

For example:

Book: (Id, Name, AuthorName, PublishDate)

Return all records in Book table that if the books are grouped by the AuthorName , they are the fifth or later books of that specific author.

I'm using MS SQL Server 2016.

Answer 1

The solution to this is basically the same as Get top 1 row of each group , however, instead of = 1 you want >=5 :

WITH CTE AS(
    SELECT {Columns}
           ROW_NUMBER() OVER (PARTITION BY Author ORDER By PublishDate) AS RN
    FROM dbo.YourTable)
SELECT {Columns
FROM CTE
WHERE RN >= 5;

Answer 2

You can also use a correlated subquery for this:

select t.*
from t
where t.publishdate >= (select t2.publishdate
                        from t t2
                        where t2.author = t.author 
                        order by t2.publishdate asc
                        offset 4 fetch first 1 row only
                       );