Wrote a request

Select (Hostel.RoomsCount - Count(Rooms.RoomId)) AS FreeRooms From Rooms inner join Hostel ON (Hostel.HostelCode=Rooms.HostelCode) WHERE Hostel.HostelCode= 1

Displays error

 Column 'Hostel.HostelCode' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause.
  • function or the GROUP BY clause - Mykola Veriga

1 answer 1

 Select (Hostel.RoomsCount - Count(Rooms.RoomId)) AS FreeRooms From Rooms inner join Hostel ON (Hostel.HostelCode=Rooms.HostelCode) WHERE Hostel.HostelCode= 1 GROUP BY Hostel.RoomsCount