create trigger tjy_delete on zzyjy
for delete 
as
  begin
       update zzyxs
              set 借書量=借書量-1
               where zzyxs.借書證號 in
               (select deleted.借書證號
                from deleted)
       update zzybook
              set 庫存量=庫存量+1
                   where zzybook.ISBN in
                       (select deleted.ISBN
                           from deleted)
  end