如何使用AJAX按钮单击更新数据库中的单元格？

This code doesn't work! The console.log prints

"You are not subscribed to newsleter"

I want to be able to click the button and then it says

"You are subscribed to newsleter"

This is my HTML

<button onclick="subscribe()">Subscribe to newsletter</button>

This is my script

function subscribe(){
    $.ajax({
        url: 'php/test.php',
        success: function(data){
            console.log(data);
        }
    });
    return false;
}

This is my PHP

<?php
$myQUERY ="SELECT * FROM user";
$myQUERY .=" UPDATE user";
$myQUERY .=" SET Subscribed='1'";
$myQUERY .=" WHERE DisplayName='Henry'";

$row = mysqli_fetch_array($result);
if ($row['Subscribed'] == 1) {
    echo 'You are subscribed to newsleter';
}
else
{
    echo 'You are not subscribed to newsleter';
}
?>

In the Database, newsletter subscription is set to 1 when subscribed and 0 when not subscribed