escrevendo uma função no sql server

 declare @from datetime

 SET @from =CONVERT(DATETIME, '01/01/2000 12:00 pm') 

  CREATE FUNCTION formatit(
      @fromtime VARCHAR(50) -- varchar
       )
    RETURNS DATETIME
    AS 
    BEGIN 
    DECLARE @from datetime
     IF (CHARINDEX('NOON',@fromtime,0)) = 0 
       SET @from = CONVERT(DATETIME, @fromtime) 
     ELSE
       SET @from =CONVERT(DATETIME, '01/01/2000 12pm') 
    RETURN(@from)
    END

 SELECT dbo.formatit('04/12/2011 NOON ')