How to select values depending on an interval of time?

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I have two tables, Movies and ResrvationsOfMovies.
Movies has the column DirectorName
ReservationsOfMovies contains the columns ReservationStartDate and ReservationEndDate.

I want to select the DirectorName of all the movies, NOT INCLUDING those movies whose reservation was active a month ago.

What I have tried:

DECLARE @aMonthAgo DATE = CAST(ReservationEndDate - ReservationStartDate) AS DATE)

 SELECT movies.DirectorName
 FROM Movies movies
 INNER JOIN Reservations res ON res.IDMovies = b.IDMovies
 WHERE res.ReservationStartDate > @aMontAgo  AND res.ReservationEndDate < GETDATE();

Posted 4-Nov-20 2:03am

xhon

Updated 4-Nov-20 2:34am

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2 solutions

Solution 1

Forget the DECLARE, it will not work in the query, use the:
SQL Server DATEDIFF() Function[^]

Posted 4-Nov-20 2:31am

RickZeeland

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Richard Deeming · Accepted Answer · 2020-11-04T02:35:00

SQL

DECLARE @Today date = GETDATE();
DECLARE @aMonthAgo date = DateAdd(month, -1, @Today);

SELECT movies.DirectorName
FROM Movies movies
INNER JOIN Reservations res ON res.IDMovies = b.IDMovies
WHERE res.ReservationStartDate > @aMonthAgo AND res.ReservationEndDate < @Today;

NB: Your date range might not be exactly what you want. If the reservation started more than a month ago, but doesn't end until tomorrow, that won't be counted. Perhaps you meant:

SQL

WHERE res.ReservationEndDate > @aMonthAgo AND res.ReservationStartDate < @Today;