How to link to this to the database
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Session Id

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<?php

              $username="xxxxxxxxxxx";
              $password="xxxxxx";
              $database="mobile_app";

              mysql_connect('localhost',$username,$password);
              @mysql_select_db($database) or die("Unable to select database");

              foreach (array('courseid') as $varname) {
                $courseid = (isset($_POST[$varname])) ? $_POST[$varname] : '';
              }

            ?>


<form action="<?php echo htmlentities($_SERVER['PHP_SELF']); ?>" method="post">
<p>Course ID: <input type="text" name="courseid" value="<?php echo $courseid; ?>" /><input type="submit" value="Submit" name="submit" /></p>      <!-- Enter User Id here-->
            </form>

            <?php
    if (isset($_POST['submit'])) {
        $query = "
                     SELECT cm.CourseId, cm.ModuleId,
                     c.CourseName,
                     m.ModuleName
                     FROM Course c
                     INNER JOIN Course_Module cm ON c.CourseId = cm.CourseId
                     JOIN Module m ON cm.ModuleId = m.ModuleId
                     WHERE
                     (c.CourseId = '".mysql_real_escape_string($courseid)."')
                     ORDER BY c.CourseName, m.ModuleId
                     ";



    $num = mysql_num_rows($result = mysql_query($query));
        mysql_close()

;
?>

<?php

      $username=xxx";
      $password="xxx";
      $database="mobile_app";


      $is_there = true;

      $con = mysql_connect('localhost',$username,$password);
      @mysql_select_db($database, $con) or die("Unable to select database");

while( $is_there ){
    $id = id_generator(); // your function to generate id;
    $result = mysql_query( "SELECT SessionId FROM Session WHERE SessionId = '$id'" );
    if( mysql_num_rows( $result ) == 0 ) $is_there = false;
}




      foreach (array('courseid', 'sessionid') as $varname) {
        $$varname = (isset($_POST[$varname])) ? $_POST[$varname] : '';
      }

    ?>

    <h1>CREATING A SESSION</h1>

        <form action="<?php echo htmlentities($_SERVER['PHP_SELF']); ?>" method="post">
         <p>Course ID: <input type="text" name="courseid" value="<?php echo $courseid; ?>" /><input type="submit" value="Submit" name="submit" /></p>      <!-- Enter User Id here-->
        </form>

        <?php
if (isset($_POST['submit'])) {
    $query = "
                 SELECT cm.CourseId, cm.ModuleId,
                 c.CourseName,
                 m.ModuleName
                 FROM Course c
                 INNER JOIN Course_Module cm ON c.CourseId = cm.CourseId
                 JOIN Module m ON cm.ModuleId = m.ModuleId
                 WHERE
                 (c.CourseId = '".mysql_real_escape_string($courseid)."')
                 ORDER BY c.CourseName, m.ModuleId
                 ";

    $num = mysql_num_rows($result = mysql_query($query));
    mysql_close();

$is_there = true;

$con = mysql_connect( address , user, pass );
mysql_select_db( DATABASE , $con );

while( $is_there ){
    $id = id_generator(); // your function to generate id;
    $result = mysql_query( "SELECT * FROM your_table WHERE id = '$id'" );
    if( mysql_num_rows( $result ) == 0 ) $is_there = false;
}

<?php

              ...
              @mysql_select_db($database) or die("Unable to select database");
              $courseid = "";
              while( $is_there ){
              $courseid = id_generator(); // your function to generate id;
              $query = "
                     SELECT cm.CourseId, cm.ModuleId,
                     c.CourseName,
                     m.ModuleName
                     FROM Course c
                     INNER JOIN Course_Module cm ON c.CourseId = cm.CourseId
                     JOIN Module m ON cm.ModuleId = m.ModuleId
                     WHERE
                     (c.CourseId = '".mysql_real_escape_string($courseid)."')
                     ORDER BY c.CourseName, m.ModuleId
                     ";

              if( mysql_num_rows( $result = mysql_query($query) ) == 0 ) $is_there = false;
              }
              mysql_close();
              echo "You generated code id: " . $courseid;

              ?>...