mysql - SELECT n row FROM table1 PER table2 -

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have 2 table: cats(category) , post.
want select n post per each category.

i have tried this:

select * cat right join (select * post post.catid=cat.id limit 3 ) ...

the problem mysql not recognize cat.id inside sub query.

regards

select  a.id,          a.category,         b.description    category         inner join post b             on a.id = b.cat_id    (     select  count(*)        post c       b.cat_id = c.cat_id ,             b.id <= c.id ) <= 2

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