Data not being able to be saved into database PHP - php

Question

I have this problem here where when I press the Add button, it should save my selected choices into my table in database.
But when I press it, my table in database did not receive any data.
Did I do something wrong with my code? I need to find a right way to save the data into my designated table.
Any help would be greatly appreciated. Thanks
<?php
include "..\subjects\connect3.php";
//echo "Connection successs";
$query = "SELECT * FROM programmes_list";
$result = mysqli_query($link, $query);
?>
<form name = "form1" action="dropdownindex.php" method="post">
<table>
<tr>
<td>Select Pragramme</td>
<td>
<select id="programmedd" onChange="change_programme()">
<option>select</option>
<?php while($row=mysqli_fetch_array($result)) { ?>
<option value="<?php echo $row["ID"]; ?>"><?php echo $row["programme_name"]; ?></option>
<?php } ?>
</select>
</td>
</tr>
<tr>
<td>Select intake</td>
<td>
<div id="intake">
<select>
<option>Select</option>
</select>
</div>
</td>
</tr>
<tr>
<td>Select Subjects</td>
<td>
<div id="subject">
<select >
<option>Select</option>
</select>
</div>
</td>
</tr>
<input type="submit" value="Add" name="send">
</table>
</form>
<?php
if(isset($_POST['Add'])) {
//print_r($_POST);
$course1 = implode(',',$_POST['programmedd']);
$course2 = implode(',',$_POST['intake']);
$course3 = implode(',',$_POST['subject']);
$db->query("INSERT INTO programmes(programme_registered, intake_registered, subjects_registered)
VALUES (' ".$course1." ',' ".$course2." ', ' ".$course3." ' )");
echo $db->affected_rows;
}
?>
<script type="text/javascript">
function change_programme()
{
var xmlhttp=new XMLHttpRequest();
xmlhttp.open("GET","ajax.php?programme="+document.getElementById("programmedd").value,false);
xmlhttp.send(null);
document.getElementById("intake").innerHTML=xmlhttp.responseText;
if(document.getElementById("programmedd").value=="Select"){
document.getElementById("subject").innerHTML="<select><option>Select</option></select>";
}
}
function change_intake()
{
var xmlhttp=new XMLHttpRequest();
xmlhttp.open("GET","ajax.php?intake="+document.getElementById("intakedd").value,false);
xmlhttp.send(null);
document.getElementById("subject").innerHTML=xmlhttp.responseText;
}
</script>
//ajax.php
<?php
$dbhost = 'localhost' ;
$username = 'root' ;
$password = '' ;
$db = 'programmes' ;
$link = mysqli_connect("$dbhost", "$username", "$password");
mysqli_select_db($link, $db);
if (isset($_GET["programme"])) {
$programme = $_GET["programme"];
} else {
$programme = "";
}
if (isset($_GET["intake"])) {
$intake = $_GET["intake"];
} else {
$intake = "";
}
if ($programme!="") {
$res=mysqli_query($link, "select * from intakes where intake_no = $programme");
echo "<select id='intakedd' onChange='change_intake()'>";
echo "<option>" ; echo "Select" ; echo "</option>";
while($value = mysqli_fetch_assoc($res)) {
echo "<option value=".$value['ID'].">";
echo $value["intake_list"];
echo "</option>";
}
echo "</select>";
}
if ($intake!="") {
$res=mysqli_query($link, "select * from subject_list where subject_no = $intake");
echo "<select>";
echo "<option>" ; echo "Select" ; echo "</option>";
while($value = mysqli_fetch_assoc($res)) {
echo "<option value=".$value['ID'].">";
echo $value["subjects"];
echo "</option>";
}
echo "</select>";
}
?>

Answer 1

Your error is where you check for button click.
Change to this
If(isset($_POST['send']))
For future purposes and references, When doing the above, include the name attribute from your button and not the value attribute