Well, it needs a space between "select" and "user.name", and the terminating semicolon is redundant - but the only way to be sure is to try it.
And I'd prefer to see SQL keywords in upper case.
SELECT user.name,post.content FROM user
INNER JOIN post
ON user.id = post.user_id
ORDER BY user.name,date(date)
To complete the question though, you should be sorting by content as well, shouldn't you?