arrays and inserting data in to the database

[dbdummy]

hi, I have a form that uses two arrays one get's a list of courses from the database and one creates dates...

 

i have two questions

 

1. how do i get the $i and $d value off of the arrays to insert in to the database, but still have each know they belong in the same row?

 

2. how do i change the dates from a multiselect dates ie, Jun 3, Jun 6, and Jun 12 to 'Jun 3, 6, 12'

 

here is the snippet of code from my select page. $numposts is a value selected on an earlier page.

 

for ($i = 0; $i < $numposts; $i++){
echo "<tr> 
      <td><strong>Course</strong></td>
      <td>";
$query_course = "SELECT * FROM courses ORDER BY course_number";
$course = mysql_query($query_course) or die(mysql_error());
if (!$result) 
{
}
echo "<select name='$session_course$i' id='$session_course$i'>
          <option selected='selected'>Select Course</option>";

while ($row_course = mysql_fetch_assoc($course))
{
$cnumber=$row_course['course_number'];
$cnumberid=$row_course['course_id'];
          echo "<option value='$cnumberid$i'>$cnumber</option>";

}
echo "</select></td>
      <td> 
        <select name='session_dates$i' id='session_dates$i' multiple='multiple' size='4'>
          <option selected='selected'>Select Date(s)</option>";

$date = mktime(0,0,0);
for ($d=0; $d<365; $d++)
{
    $d1 = date('M d Y', $date);
    $d2 = date('M d Y', $date);
    echo "<option value='$d1$d'>$d2</option>\n";
    $date = strtotime('+1 days', $date);
}

        echo "</select></td>";
	}

 

below is currently is my insert statement...but currently gets the error message:

Cannot add or update a child row: a foreign key constraint fails (`prosched/prodates`, CONSTRAINT `prodates_ibfk_3` FOREIGN KEY (`session_course_id`) REFERENCES `courses` (`course_id`))

 

$dsessioncourse = $_POST["date_session_id"];
$citycourse = $_POST["session_city_id"];
$monthcourse = $_POST["session_month_year_id"];
$activecourse = $_POST["session_ative"];
$loop = count($_POST) / 2;

for ($i = 0; $i < $loop; $i++) {
if($_POST["session_course$i"]) $product[$i]["session_course"] = $_POST["session_course$i"];
}
for ($d = 0; $d < $loop; $d++) {
if ($_POST["$d1$d"]) $product[$d]["session_dates"] = $_POST["$d1$d"];
}
foreach ($product as $item) {
$course = $item["session_course"];
$sessiond = $item["session_dates"];


$query = mysql_query("INSERT INTO `prodates` (`date_session_id`, `session_month_year_id`, `session_dates`, `session_active`, `session_city_id`, `session_course_id`) 
VALUES ('$dsessioncourse', '$monthcourse', '$session_d', '$activecourse', '$citycourse', '$course')") or die(mysql_error()); 

}