Mysql query succeeds but doesnt reflect in the database - php

Question

Please guys my code isn't working and i don't know what to do anymore. All i'm trying to accomplish is a simple mysql update using php. The header query value works at the top of my code which i use to insert values in the form, but when i attempt to submit, for some reason unknown to me, my script succeeds but it doesn't update the database. The result of clicking the submit will be my "Javascript success alert" then " all the variables in my page become Undefined. My script is below.
<?php
//Catch the id from the header and query database
if(isset($_GET['id']))
$workID= mysqli_real_escape_string($connection, $_GET['id']);
$query = "SELECT * FROM music WHERE musicID = $workID";
$result= mysqli_query($connection, $query);
$row = mysqli_fetch_array($result);
$artID = $row['IDartiste'];
$query2 = mysqli_query($connection,"SELECT music.*, artiste.* FROM music INNER JOIN artiste ON music.IDartiste=artiste.artisteID WHERE artiste.artisteID = $artID");
$row2 = mysqli_fetch_array($query2);
?>
**This is the form for editing**
<form role="form" method="get" action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]);?>">
<!-- Artiste name field--> <div class="form-group">
<span><label for="topic" style="color: #55AAFF">Artiste ID: </span> <span><?php echo $row['IDartiste'];?></span></label>
<!-- Article topic field--> <div class="form-group">
<label for="topic" style="color: #55AAFF">Music title:</label>
<input type="text" class="form-control" name="title" value="<?php echo $row['musicTitle'];?>" autofocus>
</div>
<!--Article textarea--> <div class="form-group">
<label for="body" style="color: #55AAFF">Content (text):</label>
<textarea name="article" class="form-control"><?php echo $row['musicArticle'];?>
</textarea>
</div>
<!-- Upload image start--> <div class="col-ms-6 col-xs-12" >
<div class="panel panel-default">
<div class="panel-heading" style="color: #55AAFF">Upload Image</div>
<div class="panel-body">
<iframe src="fileupload.php" width="100%" style="border:none"></iframe>
</div>
</div>
</div>
<!--Image link field--> <div class="form-group">
<label for="image_link" style="color: #55AAFF">Input image link: </label>
<input type="text" name="image" value="<?php echo $row['musicPhoto'];?>" class="form-control"/>
</div>
<!-- Upload music start--> <div class="col-ms-6 col-xs-12" >
<div class="panel panel-default">
<div class="panel-heading" style="color: #55AAFF">Upload Music</div>
<div class="panel-body">
<iframe src="music_file_upload.php" width="100%" style="border:none"></iframe>
</div>
</div>
</div>
<!--Music link field--> <div class="form-group">
<label for="music_link" style="color: #55AAFF">Input music link: </label>
<input type="text" name="file" class="form-control" value="<?php echo $row['musicFile'];?>"/>
</div>
<center>....<button type="submit" class="btn btn-default" id="btnsubmit" name="btnsubmit" style="color: #55AAFF">Update</button>....</center>
<br />
</form>
This is the update script
<?php
if(isset($_GET['btnsubmit'])){
date_default_timezone_set('Africa/Lagos');
$setdate= date('Y-m-d-h-m-s');
$date= strftime($setdate);
$time= strftime('%X');
$title = $_GET["title"];
$article = $_GET["article"];
$artisteImage = $_GET["image"];
$musicFile = $_GET["file"];
$sql_music = "UPDATE kingdomjoy.music SET musicTitle = '$title',
musicFile = '$musicFile',
musicPhoto = '$artisteImage',
musicArticle = '$article',
entryDate = '$date'
WHERE musicID = '$workID' LIMIT 1";
$musicupdate = $connection->query($sql_music);
if ($musicupdate === FALSE) {
echo "Error: " . die(mysqli_error($connection));}
else {echo"<script>swal('Success! music library updated')</script>";}
}
?>