使用php将多个复选框中的值插入mysql数据库的多行中

Question

I have stayed up two nights and I haven't been able to fix this. I am new to the site as well as in PHP please forgive my inexperience. The idea is that when a user selects several courses it should be sent to the database and stored in separate rows. what happens now is that it stores only the first value twice in the database. thanks. code:

<?php
include 'core/init.php';
protect_page();
include 'includes/overall/header.php';
$user_id=$_SESSION['user_id'];
?>

<h2>Register</h2>

<?php

if(isset($_GET['success']) && empty($_GET['success'])){
    echo 'You have successfully registered!';
}
else{
        if(empty($_POST)===false){
        $course[]=$_POST['course_code'];
        $user_id= $user_data['user_id'];
        $username=$user_data['username'];

        foreach($course as $c){

        $data= '\''.implode('\',\'',$c).'\'';

        mysql_query("INSERT INTO `lenroc_ssims`.`registercourses`(`user_id`, `username`, `course_code`) VALUE ('$user_id','$username', $data)");

            header('location:courses.php?success');
            exit();
            }
        }
    ?>
    <form action="" method="post">
    <?php

    $sql = "SELECT * FROM course";
    $result = mysql_query($sql)or die(mysql_error());

    echo "<table>";
    echo "<tr><th>COURSE CODE</th><th>COURSE TITLE</th><th>UNIT</th><th>SEMESTER</th><th>LEVEL</th></tr>";

    while($row = mysql_fetch_array($result)){
    $course_code        = $row['course_code'];
    $course_title       = $row['course_title'];
    $course_unit        = $row['course_unit'];
    $semester           = $row['semester'];
    $level              = $row['level'];
    echo "<tr><td style='width: 100px;'>".$course_code."</td><td style='width: 600px;'>".$course_title."</td><td>".$course_unit."</td><td>".$semester."</td><td>".$level."</td><td><input type=\"checkbox\" name=\"course_code[]\" value=".$course_code."></td></tr>";
    } // End our while loop
    echo "</table>";
    ?>
    <input type="submit" value="Register">
    </form>

<?php
}
include 'includes/overall/footer.php';
?>

Answer 1

Your code is dangerous. It is not resistant for sql injection. You should stop using mysql_ functions and switch to mysqli or PDO.

But just to fix the bug now you can change your code in this part:

foreach($course as $c){
    mysql_query("INSERT INTO `lenroc_ssims`.`registercourses`(`user_id`, `username`, `course_code`) 
                 VALUES ('$user_id','$username', $c)");
}
header('location:courses.php?success');
exit();

Answer 2

redirection inside loop stopped the process so it did only once. for good practice do not put sql query inside loop it makes slow process.

$values = '';
foreach($course as $c){
    $values .= "('$user_id','$username', '$c'), ";
}

$values = rtrim($values, ',');
mysql_query("INSERT INTO `lenroc_ssims`.`registercourses`(`user_id`, `username`, `course_code`) VALUES {$values}");
header('location:courses.php?success');
exit();

if you don't agree, why you don't write some comment?