sql - 触发器将插入表中的行与插入前的表进行比较

Question

大家好，我想创建触发器以在插入之前将插入表中的行与表进行比较我有一个名为“ cv_langues”的表，有 2 列“ id_cv,id_langues”这是我的触发器：

alter trigger insertion_cv_langue
on cv_langues
for insert
as
begin
declare @id_langue int,@id_cv int, @inserted_langue int,@inserted_cv int,@comp int
set @comp=0
declare cv_langues cursor
for select id_langue,id_cv from cv_langues
declare inserted_cv_langues cursor
for select id_langue,id_cv from inserted

open inserted_cv_langues
fetch inserted_cv_langue into @inserted_langue,@inserted_cv //1st line to compare
close inserted_cv_langue

open cv_langues

while @@fetch_status = 0
begin
fetch cv_langues_1 into @id_langue,@id_cv // multi lines from cv_langues
if @id_langue = @inserted_langue  and @id_cv = @inserted_cv
               begin

               set @comp = @comp+1
               end

end
if @comp =2     
rollback     
close cv_langues_1
end
deallocate inserted_cv_langue
deallocate cv_langues_1

Answer 1

尝试使用唯一约束，而不是触发器：

ALTER TABLE cv_langues ADD CONSTRAINT u_IdLangues UNIQUE (id_cv, id_langues)

这将防止为同一用户插入任何重复的条目，并且比触发器更容易和更有效。