插入时触发SQL更新

Question

I need some help on creating a trigger on MySQL.

I have a table "comment":

id_comment | id_topic | comment

and the "topic" table:

id_topic | topic | comments_ammount

I need to increase comments_ammount for each insert on "comment" table which has the same id_topic of the topic.

I never used triggers, so anyone can help me?

Answer 1

well ,i am not special in mysql but i think you can do something like this

DELIMITER $$
declare @x table(id_topic int)
insert into @x   '@x hold last insert'
select * 
from comment
order by id desc
limit 1
update topic t join @x c 
on c.id_topic =t.id_topic
set  comments_ammount=comments_ammount+1
DELIMITER $$
DELIMITER ;