Question

I have this SQL Server query which I wrote to find the Movie title that has the least amount of records in the RENTAL table.

When run, it returns a resultset that is identical to the resultset I get from executing the sub-query by itself.

In other words, rather returning the single movie with the minimum RentalCount, it returns all movie titles and their corresponding RentalCount.

SELECT B.Title, MIN(B.RentalCount) AS RentalCount
FROM (
    SELECT Movie.Title, Count(*) AS RentalCount
    FROM Rental
    JOIN Dvd ON Rental.RentalID=Dvd.DvdID
    JOIN Movie ON Dvd.Movieid=movie.MovieID
    GROUP BY Movie.Title
    ) B
GROUP BY B.Title

Answer 1

The result is correct. Your subquery returns the total count for each title on the rental table. And the result will be the same on the outer query because you have grouped them by their title also.

follow-up question: what result do you want to achieved?

find the Movie title that has the least amount of records in the RENTAL table

SELECT Movie.Title, Count(*) AS RentalCount
FROM Rental
        JOIN Dvd ON Rental.RentalID=Dvd.DvdID
        JOIN Movie ON Dvd.Movieid=movie.MovieID
GROUP BY Movie.Title
HAVING Count(*) = 
    (
        SELECT MIN(t_count)
        FROM
        (
            SELECT Count(*) t_count
            FROM Rental
            GROUP BY Title
        ) a
    )

UPDATE 1

Thanks to Martin Smith for introducing me TOP....WITH TIES

SELECT TOP 1 WITH TIES Movie.Title, Count(*) AS RentalCount
FROM Rental
        JOIN Dvd ON Rental.RentalID=Dvd.DvdID
        JOIN Movie ON Dvd.Movieid=movie.MovieID
GROUP BY Movie.Title
ORDER BY RentalCount DESC

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