Why isn't the second mysqli_fetch_assoc executing? - php

Question

I have 2 tables, comments and gossips.
Gossips has 3 columns: id, userid, gossip.
Comments has 4 columns: id, userid, gossipid, comment.
I wrote this code so that the program echos all the gossips and the comments specific to each gossip.
$query = 'SELECT * FROM gossips ORDER BY id DESC LIMIT 0,10';
$result = mysqli_query($cxn, $query)
or die("Couldn't execute query");
while($row = mysqli_fetch_assoc($result))
{
echo '<div class="gossip">'.$row['gossip'].'</div><form action="comment.php" method="post"><input type="hidden" name="gossipid" value="'.$row['id'].'" />';
echo '<input type="text" name="comment" placeholder="Write your comment here"/><br /><input type="submit" value="Comment" /></form><br />';
$querycomment = "SELECT * FROM comment WHERE gossipid ='{$row['id']}' ORDER BY id DESC";
$resultcomment = mysqli_query($cxn, $query)
or die("Couldn't fetch comments.");
while($comments = mysqli_fetch_assoc($resultcomment))
{
echo $comments['comment'];
}
}
The output of this code is only echoing the gossips and isn't executing the second while loop. What could be the problem ?

Answer 1

You go through the entire $resultcomment result set the first time you go around that loop. When the SECOND iteration of the outer $result loop starts up, there's no more data to be fetched from that second query, so in effect the inner loop only ever runs for that FIRST record from the $result set.
Since you seem to be filtering the inner loop's results using the outer loop's data, why not base that inner query on the same data, so you don't suck across your entire comment table and throw away everything EXCEPT for the matching records? That's a hideous waste.
Something more like
SELECT * FROM gossips
while(fetch gossip) {
SELECT * FROM comment WHERE id = gossip.id
}
This is somewhat more efficient, since you fetch only the comments you'd actually want to display. A further optimization would be to rewrite both queries as a single JOIN query, with some looping logic to detect when you change between gossips.