SqlServer里做试图的时候怎样添加外连接？？

Question

帮忙看看
http://www.csdn.net/expert/topic/672/672817.xml?temp=.4878961
谢谢

Answer 1

select ... from 表1 left join 表2 on 表1.b=表2.f

Answer 2

SELECT dbo.RoomIncome.Id, dbo.GuestInfo.GuestName, dbo.RoomIncome.GuestId, 
      dbo.RoomIncome.RoomId, dbo.RoomIncome.GuestStayTime, 
      dbo.RoomIncome.GuestLeaveTime, dbo.RoomIncome.GuestStayType, 
      dbo.RoomIncome.GroupId, dbo.RoomIncome.CheckOut, dbo.RoomIncome.Money, 
      dbo.RoomTypeInfo.TypeRoomName, dbo.RoomTypeInfo.RoomBedNum, 
      dbo.RoomTypeInfo.RoomPrice, dbo.RoomTypeInfo.AddBedPrice, 
      dbo.RoomTypeInfo.HourPrice
FROM dbo.RoomIncome INNER JOIN
      dbo.RoomInfo ON dbo.RoomIncome.RoomId = dbo.RoomInfo.RoomId INNER JOIN
      dbo.RoomTypeInfo ON 
      dbo.RoomInfo.TypeRoomId = dbo.RoomTypeInfo.TypeRoomId INNER JOIN
      dbo.GuestInfo ON dbo.RoomIncome.GuestId = dbo.GuestInfo.GuestId
WHERE (dbo.RoomTypeInfo.EffectFlag = 1) AND (dbo.RoomIncome.CheckOut = '0')有100条左右记录。SELECT dbo.RoomIncome.Id, dbo.RoomIncome.GuestId, dbo.RoomIncome.RoomId, 
      dbo.RoomIncome.GuestStayTime, dbo.RoomIncome.GuestLeaveTime, 
      dbo.RoomIncome.GuestStayType, dbo.RoomIncome.GroupId, 
      dbo.RoomIncome.CheckOut, dbo.RoomIncome.Money, 
      dbo.GroupInfo.GroupName
FROM dbo.RoomIncome INNER JOIN
      dbo.RoomInfo ON dbo.RoomIncome.RoomId = dbo.RoomInfo.RoomId INNER JOIN
      dbo.RoomTypeInfo ON 
      dbo.RoomInfo.TypeRoomId = dbo.RoomTypeInfo.TypeRoomId INNER JOIN
      dbo.GuestInfo ON dbo.RoomIncome.GuestId = dbo.GuestInfo.GuestId INNER JOIN
      dbo.GroupInfo ON dbo.RoomIncome.GroupId = 
dbo.GroupInfo.GroupId
WHERE (dbo.RoomIncome.CheckOut = '0')就只能查找到很少的几条记录。因为dbo.RoomIncome.GroupId可能为空的。为空的话就不能被查找出来了。请问我的视图语句应该怎么改才能达到我的要求。