另一个需求是需要当对表blocks_infos做相关处理的时候，会触发另一个表bidinfo.v_publish_info 做相应的处理，因为前面已经建立了after insert on blocks_infos，不能再建立 after insert
on blocks_infos,所以只能创建 before insert on blocks_infos，如下创建了三个：
1)insert
DELIMITER $
create trigger tri_insert_blocks_infos1 before insert
on blocks_infos for each row
begin
DECLARE d int;
set d=(select intc from bidinfo.v_publish_info where id=new.infos_id);
if d is null then
update bidinfo.v_publish_info set intc=1 where id= new.infos_id;
else
update bidinfo.v_publish_info set intc=intc+1 where id= new.infos_id;
end if;
end $
DELIMITER ;
2)delete
DELIMITER $
create trigger tri_delete_blocks_infos1 before delete
on blocks_infos for each row
begin
DECLARE h int;
set h=(select intc from bidinfo.v_publish_info where id=old.infos_id);
if h is null then
update bidinfo.v_publish_info set intc=1 where id= old.infos_id;
else
update bidinfo.v_publish_info set intc=intc+1 where id= old.infos_id;
end if;
end $
DELIMITER ;
3)update ，注意可以只用两个if循环！
DELIMITER $
create trigger tri_update_blocks_infos1 before update
on blocks_infos for each row
begin
DECLARE j int;
DECLARE i int;
set i=(select intc from bidinfo.v_publish_info where id=new.infos_id);
set j=(select intc from bidinfo.v_publish_info where id=old.infos_id);
if j is null then
update bidinfo.v_publish_info set intc=1 where id= old.infos_id;
else
update bidinfo.v_publish_info set intc=intc+1 where id= old.infos_id;
end if;
if i is null then
update bidinfo.v_publish_info set intc=1 where id= new.infos_id;
else
update bidinfo.v_publish_info set intc=intc+1 where id= new.infos_id;
end if;
end $
DELIMITER ;
小结：触发器中的new和old,可以理解为处理过的整行数据，可以通过new.字段名来取出那个字段的值，并且alter和before都不能修改old的值，但是before可以修改new的值，还需要注意对同一个表的相同触发时间(after/before)的相同触发事件(insert/update/delete)，只能定义一个触发器，并且before的形式的触发器需要保证触发端和被触发端都得成功才能成功！