PHP - Variable Not Changing When It Should - From Null

I am trying to get a simple thing working.  I have a domain with google that I want to change the point to IP when I access a PHP page.  I have a DB table with settings that I am using for the username, password, etc.  The issue is that the command to change the IP always sends the same IP.  No matter what I try.  I have tried assigning a fixed entry for the variable $localip, I have set that variable to 0 ahead of the query to get the info from the table.  Nothing I do will change the variable in the command.  I can manually put the command in a browser and it will perform the change.  Can anyone comment on what I am missing here?

<?php
ini_set("display_errors", 1);
ini_set("track_errors", 1);
ini_set("html_errors", 1);
error_reporting(E_ALL); 
require('/var/www/html/cqadmin/utils/connect.php');

$sql = "SELECT * FROM `failover` LIMIT 0, 30";
$result = mysqli_query($link,$sql) or die(mysql_error());
$row = mysqli_fetch_array($result);
$localip = ($row['localip']);
$dnsusername = ($row['dnsusername']);
$dnspassword = ($row['dnspassword']);
$domain = ($row['failoverurl']);
$location = ($row['location']);
$dealer = ($row['dealer']);
$output = shell_exec("curl -s https://$dnsusername:$dnspassword@domains.google.com/nic/update?hostname=$domain&myip=$localip");
mysqli_close($link);
?>

I get no errors on the page and if I echo $output I get a nochng message back from Google

Thanks for looking!!

 $("#lblpasswordmessage").html("Password is too short"); 

 $("#pwm").html("Password is too short"); 
 $("pwm").html("Password is too short"); 
 $(pwm).html("Password is too short"); 

2 PART QUESTION (so I don't have to ask two questions 😀  )

1.)
My script has tons of PHP variables. Is it better to declare them all at the top of my page like this:
$cat = $words = $day = $lunch = $user = $address = $potato = $_SESSION["goodpeople"] = $dumbquestionList = $b = $hundredMoreVariables = "";
-or-
as needed, like this:
$cat = "";  if($day == 'Thursday') { $cat = 'time_to_feed'; }
$words = "";  $school = array('teachers'=>'boring','lunch'=>'free'); $words = $school['teachers'];
$_SESSION["goodpeople"] = ""; if($_SESSION["goodpeople"] == "" { $_SESSION["goodpeople"] = 'Gandhi'; }

2.)
What are the pros and cons of declaring variables as NULL and using " isset " versus declaring variables as "" and using ==
Example:
$cat = $words = $day = $lunch = $user = $address = NULL;
if( !isset($cat)) { $cat = 'black'; }.........................if(isset($day)) { $sleep = 'none'; }..............etc., etc.
-or-
$cat = $words = $day = $lunch = $user = $address = "";
if($cat == "") { $cat = 'black'; }............................ if($day != "") { $sleep = 'none'; }................etc., etc.

On my particular coding, I can use either the NULL/isset style, or, the ""/== style, with no errors or ill effects.... but something tells me the expert PHP coders prefer one over the other...

Thank you!!

SELECT IFNULL(trans, 0) AS 'Transactions', customer.cID AS 'Customer ID', customer.surname AS 'Surname'
FROM customer
LEFT JOIN account
ON (account.cID = customer.cID)
WHERE IFNULL(trans, 0);

$sql = "SELECT SUM(IF(`submitdate` IS NULL , 1 , 0 )) as 'Survey Started But Not Completed' FROM `survey_$surveyid`";
$statement = $dbh->prepare($sql);
$statement->execute();
$result = $statement->fetch(PDO::FETCH_OBJ); //pass that data to an object

stdClass Object
(
    [Survey Started But Not Completed] => 
)

$result  = 0;

$result = array(['Survey Started But Not Completed'] => "0");