关于SQL Server事务递交及回滚

declare @err int
set @err = 0        
begin 
  begin transaction tc 
  insert into TWeb_Uff_Box(BoxCode) values('1')
  set @err = @err + @@error

  insert into TWeb_Uff_Box(BoxCode) values('2')
  set @err = @err + @@error

  insert into TWeb_Uff_Box(BoxCode) values('3')
  set @err = @err + @@error

  if(@err > 0)
    rollback transaction tc
  else
    commit transaction tc

end