sql - Access count on another table doesn't work -

i have posts table , postcomments table of blog system. want count , sort posts comment count query won't work.:

select posts.postid, posts.datecreated, posts.title, posts.description, posts.hits, (select count(commentid) postcomments  postcomments.postid=posts.postid , postcomments.isapproved=true) commentcount posts order posts.postid desc; 

i tried:

select posts.postid, posts.datecreated, posts.title, posts.description, posts.hits, count([commentid]) commentcount posts inner join postcomments on posts.postid = postcomments.postid; 

but have error "you tried execute query not include specified expression 'postid' part of aggregate function."

i'm complete access noob, try second 1 grouping non-aggregated columns.

    select         posts.postid        ,posts.datecreated        ,posts.title        ,posts.description        ,posts.hits        ,count([commentid]) commentcount      posts         inner join postcomments on posts.postid = postcomments.postid     group        posts.postid        ,posts.datecreated        ,posts.title        ,posts.description        ,posts.hits    order       count([commentid]); 

maybe have put join row braces in ms-access.