psuedo code:

func postData()//client
{
	var yourData = getDataForRow();/* or however your data is stored, as long as you make it compatible with however the you want the db to store it */
	var xhttp = new XMLHttpRequest();//i forgot what its actually called, look it up
	xhttp.open("POST", "http://endpoint.for.your.database/post.php", true);/*the post url is whatever you want it to be as long as that script deals with actually putting it in a db*/
	xhttp.setRequestHeader("", "");//if you're sending json, set appropriate header
	xhttp.send(yourData);
}

func receivePostedData()//server
{
	$conn = new mysqli($servername, $username, $password, $dbname);
	// Check connection
	if ($conn->connect_error) {
	    die("Connection failed: " . $conn->connect_error);
	}

	$sql = ""; //your sql insert command

	if ($conn->query($sql) === TRUE) {
    	echo "New record created successfully";
	} else {
    	echo "Error: " . $sql . "<br>" . $conn->error;
	}

	$conn->close();
}