Question

I have the following database design:

Users Table: NetworkID, Name, BadgeNo, DepartmentCode
Events Table: ID, Title, Description, Location, StartDateTime, EndDateTime, NumberOfSeats, IsActive
BookingDetails Table: BookingID, EventID, NetworkID

I need to come up with a query that shows the number of seats, number of bookings and number of remaining (or availble) seats in each event. I wrote a query that shows the number of seats and number of bookings. Now, I need to find the number of remaining (or available) seats which is equal to (number of seats – number of bookings). So could you please help me in modifying it to find this requirement?

My Query:

SELECT     dbo.Events.Title, dbo.Events.Description, dbo.Events.Location, dbo.Events.NumberOfSeats, COUNT(DISTINCT dbo.BookingDetails.NetworkID) 
                      AS [Number of Bookings]
FROM         dbo.BookingDetails INNER JOIN
                      dbo.Users ON dbo.BookingDetails.NetworkID = dbo.Users.NetworkID RIGHT OUTER JOIN
                      dbo.Events ON dbo.BookingDetails.EventID = dbo.Events.ID
WHERE     (dbo.Events.IsActive = 1)
GROUP BY dbo.Events.Title, dbo.Events.Description, dbo.Events.Location, dbo.Events.NumberOfSeats

Answer 1

SELECT     dbo.Events.Title, dbo.Events.Description, dbo.Events.Location,
           dbo.Events.NumberOfSeats, COUNT(DISTINCT dbo.BookingDetails.NetworkID) AS [Number of Bookings],
           dbo.Events.NumberOfSeats - COUNT(DISTINCT dbo.BookingDetails.NetworkID) AS RemainingSeats
FROM         dbo.BookingDetails INNER JOIN
                      dbo.Users ON dbo.BookingDetails.NetworkID = dbo.Users.NetworkID RIGHT OUTER JOIN
                      dbo.Events ON dbo.BookingDetails.EventID = dbo.Events.ID
WHERE     (dbo.Events.IsActive = 1)
GROUP BY dbo.Events.Title, dbo.Events.Description, dbo.Events.Location, dbo.Events.NumberOfSeats