declare @coun int
declare @str varchar(5)
declare @a int
create table #temptable(val int)
select @coun = count(*) from syscolumns where id = object_id('tablename')
while(@coun > 0)
begin
	select @str = name from syscolumns where colid = @coun and id = object_id('tablename')	
  	insert into #temptable exec ('select '+ @str + ' from tablename')
	set @coun = @coun - 1	
end
select max(val) from #temptable