PHP: if-else statement and mysql_num_rows not working - php

Question

I'm working on a web page where a user will be allowed to add or edit a feedback for a place. If the person already gave the place a feedback, he/she will be shown an Edit Review button otherwise, the user will be shown an Add Review button.
In my feedback table in my database, I have a places_id and users_id column. Here's my query in PHP (Assuming that $id and $places_id have values):
<?php
$query5 = mysql_query("SELECT * FROM feedback WHERE user_id = '$id' AND places_id = '$places_id'");
$row5 = mysql_fetch_array($query5);
if($row5['user_id'] != $id){
?>
<button type="button" class="btn btn-default"><span class="glyphicon glyphicon-arrow-left"></span> Back</button>
<button class="btn btn-primary" type="submit" name="submit">Review</button>
<?php }else{ ?>
<button type="button" class="btn btn-default"><span class="glyphicon glyphicon-arrow-left"></span> Back</button>
<button class="btn btn-primary" type="submit" name="submit">Edit Review</button>
<?php } ?>
I was thinking that if the query did not return a result where the given user_id is not equal to the user_id in the result, it would let me do my if-else condition. However if there is a feedback for a current place, it displays the button found in the else statement.
What do you think is the problem and why is the if condition not working?
I also tried if(mysql_num_rows($query5)==0) but it's also not working.

Answer 1

I would always do:
<?php
$query5 = mysql_query("SELECT * FROM feedback WHERE user_id = '$id' AND places_id = '$places_id'");
if ($row5 = mysql_fetch_array($query5)) {
?>
<button type="button" class="btn btn-default"><span class="glyphicon glyphicon-arrow-left"></span> Back</button>
<button class="btn btn-primary" type="submit" name="submit">Edit Review</button>
<?php }else{ ?>
<button type="button" class="btn btn-default"><span class="glyphicon glyphicon-arrow-left"></span> Back</button>
<button class="btn btn-primary" type="submit" name="submit">Review</button>
<?php } ?>