表值函数,标量值函数

表值函数：
ALTER FUNCTION getTable( )
RETURNS TABLE AS
RETURN ( select * from tb）
取值：select * from getTable( )
标量函数：
ALTER FUNCTION [dbo].[CamOnlineAverage]   (
      @projId INT ,
      @startDate DATETIME ,
      @endDate DATETIME
    )
RETURNS  Float AS
Begin
    DECLARE @result FLOAT,@s int,@t int;
    SELECT  @s=SUM(SumTime) ,@t=SUM(TotalTime)  FROM   dbo.tb_CamOnlineDetail(@projid,@startDate,@endDate)
    IF(@t=0)begin RETURN 0.0 END   
    RETURN @s*100.0/@t
End

取值：select CamOnlineAverage(1212,'2016-5-5','2016-8-8')