Ain't echo when row doesn't exist in PHP - php

Question

<tr>
<td id="idtypesectype2">Skype</td>
<td id="doubledotsec">:</td>
<td>
<?php
$search = $_GET['search'];
$sql ="SELECT * FROM contact_info WHERE CU_id='$search' AND contact_information_type='social_media_skype' AND visibility='1'";
$result = $db -> query($sql);
WHILE ($row=$result->fetch_assoc()) {
if(mysqli_num_rows($result) < 0) {
echo "-";
} else {
echo $row['contact_information'];
}
?><br>
<?php
}
?>
</td>
</tr>
I don't get - when the row is empty, instead it is a blank. Can you help me with this isuue? I want that it will show - when the row doesn't exist.

Answer 1

You're checking how many rows your query returns in your while loop, where you fetch the single rows. Yet, if there are none, you never get in the while loop.
So, what you need to do, is put your if condition before the while, and the while loop inside the else statement.
First, you have to remember that a while loop with nothing to process just terminates and continues with the code after it. So if you want to test the number of rows in the resultset, you need to do it before running the while loop
You also need to use prepared queries to protect yourself from SQL Injection Attack
<tr>
<td id="idtypesectype2">Skype</td>
<td id="doubledotsec">:</td>
<td>
<?php
$sql ="SELECT *
FROM contact_info
WHERE CU_id=?
AND contact_information_type='social_media_skype'
AND visibility='1'";
# prepare and bind parameter to the query to protect against SQL Injection
$stmt = $db->prepare($sql);
$stmt->bind_param('i', $_GET['search']);
$stmt->execute();
$results = $stmt->get_result();
if($result->num_rows == 0) {
echo "-";
}
while ($row=$result->fetch_assoc()) {
echo $row['contact_information'];
}
?>
<br>
</td>
</tr>

Answer 2

I think you must change your code to this to get the disired result:
<tr>
<td id="idtypesectype2">Skype</td>
<td id="doubledotsec">:</td>
<td>
<?php
$search = $_GET['search'];
$sql ="SELECT * FROM contact_info WHERE CU_id='$search' AND contact_information_type='social_media_skype' AND visibility='1'";
$result = $db -> query($sql);
if($result->num_rows < 0) {
echo "-";
} else {
WHILE ($row=$result->fetch_assoc()) {
echo $row['contact_information'];
}
?><br>
<?php
}
?>
</td>
</tr>