The following query should return all rooms that don't have scheduled meetings for a given date. You can add it to your query using UNION ALL, if it works as intended.

SELECT corooms.roomid, @DateTimeBegin, @DateTimeEnd 
FROM  dbo.coproc INNER JOIN
      dbo.coProcRoomGrp ON dbo.coproc.procid = dbo.coProcRoomGrp.procID INNER JOIN
      dbo.coRoomToGroup ON dbo.coProcRoomGrp.coRoomGrpID = dbo.coRoomToGroup.coRoomGrpID INNER JOIN
      dbo.corooms ON dbo.coRoomToGroup.RoomID = dbo.corooms.roomid
WHERE dbo.coproc.procid = @tiProcID 
	AND NOT EXIST ( SELECT * FROM meetings 
		WHERE coRooms.RoomID = meetings.roomID 
			AND meetings.beginTime BETWEEN @DateTimeBegin, @DateTimeEnd)

I didn't tested it.

>I have a table that holding meeting information. I am trying to write a stored procedure that will bring back the Begining and ending of open slots by room id for a given date. So if I pass it a begintime,endtime (both date and time fields) then I want to search the meetings table for openings. To make it a little trickier, we pass a procedure ID that and have a query that returns the rooms that the procedure can be done in. Below is the code i'm using that basicly works. I mean it does exactly what it is told to do. The problem with this code, is that it only returns records where there is a least one thing scheduled for the selected date in a room. If a room on that date doesn't have anything scheduled, it doesn't return a record for it.
>
>

>DECLARE @tiProcID int
>DECLARE @Gap int
>DECLARE @DateTimeBegin datetime
>DECLARE @DateTimeEnd datetime
>
>SET @tiProcID = 7141
>SET @gap = 90
>SET @DateTimeBegin = '07/01/2002 07:00'
>SET @DateTimeEnd =   '07/01/2002 17:00'
>
>SELECT 	m1.roomid,DATEADD(minute, 1, m1.endTime) AS OpenTimeBegin,
>	DATEADD(minute, @gap, m1.endTime) AS OpenTimeEnd
>FROM meetings m1
>LEFT JOIN meetings m2 ON ISNULL(m2.beginTime, @DateTimeEnd) > m1.endTime
>	AND (m1.roomID = m2.roomID OR m2.roomID IS NULL)
>WHERE DATEDIFF(minute, m1.endTime, ISNULL(m2.beginTime, @DateTimeEnd)) >= @gap+1
>and m1.begintime between @dateTimeBegin and @dateTimeEnd
>AND ISNULL(m2.beginTime, @DateTimeEnd) =
>	( SELECT MIN(m3.beginTime)
>	   FROM meetings m3
>	   WHERE m3.beginTime >= m1.endTime AND (m3.roomID = m2.roomID OR m2.roomID IS NULL))
>and exists ( SELECT corooms.roomid
>FROM  dbo.coproc INNER JOIN
>      dbo.coProcRoomGrp ON dbo.coproc.procid = dbo.coProcRoomGrp.procID INNER JOIN
>      dbo.coRoomToGroup ON dbo.coProcRoomGrp.coRoomGrpID = dbo.coRoomToGroup.coRoomGrpID INNER JOIN
>      dbo.corooms ON dbo.coRoomToGroup.RoomID = dbo.corooms.roomid
>WHERE dbo.coproc.procid = @tiProcID
>and coRooms.RoomID = m1.roomID)
>

>
>Thanks for any help.
>
>Kirk