delete a from a inner join b on a.a1=b.b1 and a.a2=b.b2
delimiter // create trigger mike before insert on b for each row bin delete from a where a.a1=new.b1 and a.a2=new.b2; end // delimiter ;
从一表a中随即抽取10个值插进表b(b1,b2)中,表中a(a1,a2)没有主键,a1可以重复, insert into b(b1,b2) select a1,a2 from a order by rand() limit 10;怎么实现在A中删除掉b中新插入的数据? delete from a where exists (select 1 from b where b1=a.a1 and b2=a.a2);如果是要触发器,则按二楼的就可以了。
create trigger mike before insert on b
for each row
bin
delete from a where a.a1=new.b1 and a.a2=new.b2;
end
//
delimiter ;
insert into b(b1,b2) select a1,a2 from a order by rand() limit 10;怎么实现在A中删除掉b中新插入的数据?
delete from a where exists (select 1 from b where b1=a.a1 and b2=a.a2);如果是要触发器,则按二楼的就可以了。