Replaceing mysqli query in while loop with one query using JOIN - php

Question

I often read that mysql(i) queries used in while loops are not really performance friendly and I'm going to rewrite my code because I think it get better. But here's my question if a JOIN can work here. It's a single post viewing function but you should see every comment which got posted below. I got the comment loop in the loop which the post is printed.
<?php
$result = (empty($_GET['hash'])) ? $_GET['hash'] = '' : mysqli_query($conn, "SELECT * FROM `userposts` WHERE `hash`='".$_GET['hash']."' LIMIT 1");
while($rows = mysqli_fetch_array($result)){
//Output of single post
$commentresult = mysqli_query($conn, "SELECT * FROM `comments` WHERE `postid`='".$rows['id']."'");
while($commentrows = mysqli_fetch_array($commentresult)){
//Output of all comments
}
}
So I think it gets better but the query with JOIN should be like:
$result = (empty($_GET['hash'])) ? $_GET['hash'] = '' : mysqli_query($conn, "SELECT * FROM `userposts` JOIN comments ON userposts.id = comments.postid WHERE `hash`='".$_GET['hash']."' LIMIT 1");
But if I'm trying to post the data of the comments in the while loop which is the singlepost printed it just prints one comment. So what can I do?
regards

Answer 1

Your code is a bit of a mess. You are sometimes call mysql_fetch_results with a string, which is weird.
What you want is this:
"SELECT * FROM comments LEFT JOIN userposts ON comments.PostID = userposts.ID WHERE userposts.Hash = '$_GET['hash']'"
EDIT: sorry, you want LEFT JOIN with comments on the left. Gives you all the comments
EDIT 2: I set this up and it worked as I expected, even with multiple posts with the same hash.
<?php
$hash = $_GET['hash'];
$result = mysqli_query($conn, "SELECT * FROM comments LEFT JOIN userposts ON comments.PostID = userposts.ID WHERE userposts.Hash = '$hash'");
if ( $row = mysql_fetch_array($result)) {
// output of post.
// output first comment
}
while($row = mysqli_fetch_array($result)){
//Output other comments
}
?>