Commit cacb5d03 authored by Sorrel Harriet's avatar Sorrel Harriet
Browse files

updating add track script with transaction example

parent d75f3f87
// include the HTML for the page header
include "templates/header.html";
// include the HTML for the navigation bar
include "templates/nav.html";
// open a new MySQL database connection
require "includes/db_connect.php";
// require the helper functions script
require "includes/functions.php";
// check if 'page' parameter is set in query string
if (isset($_GET['page'])) {
$page = $_GET['page']; // if so, set page variable to value of 'page' parameter
} else {
$page = 'home'; // if not, set page variable to home
// define a variable to store content HTML
$content = "";
// determine which view to serve based on value of $page
switch ($page) {
case 'home' :
include 'views/home.php';
case 'albums' :
include 'views/albums.php';
case 'album' :
include 'views/album.php';
case 'add-track' :
include 'views/add-track.php';
default :
include 'views/404.php';
// close the connection to the database */
// output the HTML
echo $content;
include "templates/footer.html";
$content = "<h1>Add a track</h1>";
// define a variable with path to the script which will process form
// -> $_SERVER["PHP_SELF"] is a path to the current script (index.php)
$action = $_SERVER["PHP_SELF"]."?page=add-track";
// turn autocommit off
mysqli_autocommit($link, FALSE);
// start a transaction
mysqli_query($link, 'START TRANSACTION');
// fetch the albums so that we have access to their names and upc's
// apply LOCK IN SHARE MODE to ensure the upc's will be valid
// at the point we COMMIT the transaction
$sql = "SELECT upc, title
FROM Album
$result = mysqli_query($link, $sql);
// check query returned a result
if ($result === false) {
echo mysqli_error($link);
} else {
$options = "";
// create an option for each artist
while ($row = mysqli_fetch_assoc($result)) {
$options .= "<option value='".$row['upc']."'>";
$options .= $row['title'];
$options .= "</option>";
// define the form HTML (would ideally be in a template)
$form_html = "<form action='".$action."' method='POST'>
<label for='t_name'>Name:</label>
<input type='text' name='t_name' required>
<label for='t_number'>Track number:</label>
<input type='number' name='t_number' min='1' max='25'>
<label for='a_upc'>Album:</label>
<select name='a_upc' required>
<option value='' disabled selected>Select an album</option>
<button type='submit'>Submit</button>
// append form HTML to content string
$content .= $form_html;
// ------- START form processing code... -------
// define variables and set to empty values
$title = $artist_id = $price = $year = $genre = "";
// check if there was a POST request
// validate the form data
$a_upc = mysqli_real_escape_string($link, clean_input($_POST["a_upc"]));
$t_name = mysqli_real_escape_string($link, clean_input($_POST["t_name"]));
$t_number = mysqli_real_escape_string($link, clean_input($_POST["t_number"]));
// define the insertion query
$sql = sprintf("INSERT INTO Track (album_upc, name, track_number)
VALUES ('%s', '%s', %d)", $a_upc, $t_name, $t_number);
// run the query to insert the data
$result = mysqli_query($link, $sql);
// check if the query went ok
if ($result === false) {
mysqli_rollback($link); // if query returns false, rollback transaction
// handle specific errors based on mysli error number code
// (in order to output more useful message to user!)
$errno = mysqli_errno($link);
switch ($errno) {
case 1062 : // case for duplicate entry
$content .= "There is already a track with that name or number.";
default :
echo mysqli_error($link);
} else {
mysqli_commit($link); // else, commit transaction
$content .= "Track successfully added.";
// ------- END form processing code... -------
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