mysql - How to get a unique value from a column while returning the most recent non unique -

i have group of tables this:

post_id | post_content | page_id         1         etc...        7    2         text...       5 

and

changelog_id | post_id | page_id |   changelog_date    | changelog_type       1               2        5       02/02/2015 11:05         3       2               2        5       02/02/2015 11:15         2       3               1        7       03/01/2015 18:15         3 

i want return:

select distinct post_id, post_content, changelog_type, changelog_date posts p  inner join logs l on l.post_id = p.post_id p.page_id = 5 

but distinct wont wort because changelog_date not unique. want return like:

 post_id| post_content |  changelog_type   | changelog_date    2        text...      02/02/2015 11:15         2 

with recent entry of post_id page_id , 1 result per post_id.

i tried group by, get:

column 'page.pageid' invalid in select list because not contained in either aggregate function or group clause.

in actual use have 6 tables information , using inner join information them all. need reduce returns getting 1 per instance of post_id.

try this:-

select distinct post_id, post_content, changelog_type, max(changelog_date) posts p  inner join logs l on l.post_id = p.post_id p.page_id = 5 group post_id, post_content, changelog_type