create trigger tg_tb on Gbaozhuangjihua    
after insert,update
as
begin
update a
set a.包装ID = b.id
from Gbaozhuangjihua a join gbaozhuangxingxi b on a.包装代码 = b.包装代码
where b.id <> a.包装ID
end

------解决方案--------------------

SQL code

create table gbaozhuangxingxi 
(包装ID int, 包装代码 varchar(20), 数量 int, 单位 varchar(10))

insert into gbaozhuangxingxi
select 1, 'ZX-10-10-1-CPT', 20, '件/箱' union all 
select 2, 'ZX-10-10-2-CPT', 30, '件/箱' union all 
select 3, 'ZX-10-10-3-CPT', 40, '件/箱' union all 
select 4, 'ZX-10-10-4-CPT', 50, '件/箱'

create table Gbaozhuangjihua 
(包装计划ID int, 包装代码 varchar(20), 计划数 int, 包装ID int)

insert into Gbaozhuangjihua
select 1, 'ZX-10-10-1-CPT', 5, 1 union all 
select 2, 'ZX-10-10-2-CPT', 6, 2 union all 
select 3, 'ZX-10-10-3-CPT', 7, 3 union all 
select 4, 'ZX-10-10-4-CPT', 8, 4 

create trigger tr_Gbaozhuangjihua 
on Gbaozhuangjihua
for update
as
begin
 if update(包装代码)
 begin
   if exists(select 1 from gbaozhuangxingxi a 
             inner join inserted b on a.包装代码=b.包装代码)
      update a set a.包装ID=
             (select a.包装ID from gbaozhuangxingxi a 
              inner join inserted b on a.包装代码=b.包装代码)
      from Gbaozhuangjihua a
      inner join inserted b on a.包装计划ID=b.包装计划ID
   else
   begin
      print '包装代码表中不存在相应代码信息.'
      rollback tran
   end   
 end
end


-- 测试更新为 ZX-10-10-2-CPT
update Gbaozhuangjihua set 包装代码='ZX-10-10-2-CPT' where 包装计划ID=3

select * from Gbaozhuangjihua

包装计划ID      包装代码            计划数        包装ID
----------- -------------------- ----------- -----------
1           ZX-10-10-1-CPT       5           1
2           ZX-10-10-2-CPT       6           2
3           ZX-10-10-2-CPT       7           2
4           ZX-10-10-4-CPT       8           4


-- 测试更新为不存在的包装代码
update Gbaozhuangjihua set 包装代码='abc' where 包装计划ID=3

select * from Gbaozhuangjihua

包装计划ID      包装代码            计划数        包装ID
----------- -------------------- ----------- -----------
1           ZX-10-10-1-CPT       5           1
2           ZX-10-10-2-CPT       6           2
3           ZX-10-10-2-CPT       7           2
4           ZX-10-10-4-CPT       8           4

------解决方案--------------------
探讨

兄弟，有一个问题，就是一改这条记录把我gbaozhuangxingxi表中的所有包装ID给改完了，不对啊，我只需改对应这条的包装ID