创建触发器出的语法错误！求大神解答！

CREATEtrigger books_in
on BooksIN
for insert
as
declare @bID int,@num int
/*@bID：入库的图书ID, @num:入库数量 */
select @bID=bookID,@num= num from inserted
/*判断库存表中是否存在当前入库的图书*/
if exists(select * from BooksStorage where bookID=@bID)
/*存在，修改原记录*/
update BooksStorage
set storage= storage +@num
where bookID=@bID
else
/*没有，插入新记录*/
insert BooksStorage(bookID, storage)
values(@bID,@num)

你找到解决方法了吗 我也是 着急