Writing a better code / query - php

Question

In my website, user's can update and other can comment on the updates, as usual like other social networking websites..
What am doing :
query = fetches first name, last name, user id, update id, update post UNION same details for the user who has logged in i.e /* Updates Of Current Logged In User + Updates Of People He Is Following */
loop {
prints first name last name and update
}
later I introduced commenting feature so now what I do is in the loop I call a query and run a loop again for comments..
loop {
prints first name last name and update
commentquery = fetches firstname, last name, user id, comment, of the particulat post
again loop {
prints first/last name of the person who commented, and his comment
}
}
Now according to me I guess this can be accomplished with the SQL query, that when I retrieve posts, I can fetch it's comments along with it, or is this the right way? the problem is when the outer loop runs, the inner loop also runs to fetch the appropriate comments, so can I join tables to retrieve the comments related to posts/updates?

Answer 1

This is very difficult to answer without your database structure or actual SQL but I have tried to generalise as much as possible. What you are trying to do should be done via SQL with two queries and one loop, something like below.
Edit Your fine looping and re-executing the query. You CAN fetch all this data in one go with SQL but you will duplicate allot of information in each call. For scalability and readability I would stick with two queries and two loops
/** updated after op's comments **/
SELECT data, that, you, want, for, one, post
FROM posts AS a
INNER JOIN users AS b ON b.id = a.user_id
loop over query results () {
/** output the post data **/
/** Then select the users who have posted on this post **/
SELECT a.comments, b.username
FROM comments AS a
INNER JOIN users AS b ON b.id = a.id
INNER JOIN posts AS c ON c.id = a.post_id AND c.post_id = '[post id value]'
ORDER BY a.date_posted;
loop comments here {
/** output comments here **/
}
}

Answer 2

I think merging it in only query might be possible but not nice.
But if I understand correctly what you dislike is that the query for the comments is executed with a differen WHERE clause in the loop. You could eliminate that by fetching all the comments for all the updates you are showing in one query before querying the DB for the updates:
query = select all comments for all updates joined with usernames and whatnot
loop{
$comments[postid][] = data
}
After this you do your normal query for the updates and access the comments from the preloaded array instead of from the database. Not sure if this is better solution though. On the upside you have that there is only one query for the updates, and one for the comments, and not one for the updates and one for the comments of each update.(Like 2 queries instead of 11 when you have 10 updates). Not sure if the difference is really big.
The downside is, that the code you had before was a little more obvious, and so easier to read for someone else.