Save ID from dropdown list into other table - php

Question

I have a form with fields and one dropdown list. The data from the dropdown list comes out the table: categorie. (fields are: catID, catName)
When I select a categorie from the drop down list and fill all the other input fields, it saves all the input fields and only the catName from the categorie table into the tabel: event.
How can I also save the selected catID from the categorie table into the event table?
Can someone helm me out here?
Regards, Benny
<?php require '../Connections/localhost.php'; ?>
<?php
if(isset($_POST['newEvent'])) {
session_start();
$eventName = $_POST['SelCatName'];
$eventSDate = $_POST['Event-StartDate'];
$eventSTime = $_POST['Event-StartTime'];
$eventEDate = $_POST['Event-EndDate'];
$eventETime = $_POST['Event-EndTime'];
$eventDescription = $_POST['Event-Description'];
$catID = $_POST["catID"];
$sql = $con->query("INSERT INTO event (eventName, eventSDate, eventSTime, eventEDate, eventETime, eventDescription, catID)Values('{$eventName}', '{$eventSDate}', '{$eventSTime}', '{$eventEDate}', '{$eventETime}', '{$eventDescription}', '{$catID}')");
header('Location: eventOK.php');
}
?>
<form action="" method="post" name="RegisterForm" id="RegisterForm">
<div class="FormElement">
<select name="SelCatName" class="TField" id="SelCatName">
<option selected="selected" id="0">--Selecteer een categorie--</option>
<?php
$GetAllCategories = $con->query("SELECT * FROM categorie");
while ($ViewAllCategories = mysqli_fetch_array($GetAllCategories)){
?>
<option id="<?php echo $ViewAllCategories['catID']; ?>"><?php echo $ViewAllCategories ['catName']; ?> </option>
<?php } ?>
</select>

Answer 1

You made a mistake in <option id="id"></option>
if you wanna take value from select child.
you must change id to value="" or you must add value="id" proper.
change your select box block completely like below..
<select name="SelCatName" class="TField" id="SelCatName">
<option selected="selected" id="0">--Selecteer een categorie--</option>
<?php
$GetAllCategories = $con->query("SELECT * FROM categorie");
while ($ViewAllCategories = mysqli_fetch_array($GetAllCategories)){
?>
<option value="<?PHP echo $ViewAllCategories['catID'].'-'.$ViewAllCategories['catName']; ?>"> <?PHP echo $ViewAllCategories['catName']; ?></option>
<?php } ?>
</select>
and a tip for mysql query... to the best of one's ability don't use "select * from" use it if you dont need to all colums better than "*"
$con->query("SELECT catID, catName FROM categorie");
PHP file
<?php require '../Connections/localhost.php'; ?>
<?php
if(isset($_POST['newEvent'])) {
session_start();
//$eventName = $_POST['SelCatName'];
$eventSDate = $_POST['Event-StartDate'];
$eventSTime = $_POST['Event-StartTime'];
$eventEDate = $_POST['Event-EndDate'];
$eventETime = $_POST['Event-EndTime'];
$eventDescription = $_POST['Event-Description'];
$catIDs = $_POST["SelCatName"];
$catID = explode("-", $catIDs);
$sql = $con->query("INSERT INTO event (eventName, eventSDate, eventSTime, eventEDate, eventETime, eventDescription, catID)Values('{$catID[1]}', '{$eventSDate}', '{$eventSTime}', '{$eventEDate}', '{$eventETime}', '{$eventDescription}', '{$catID[0]}')");
header('Location: eventOK.php');
}
?>

Answer 2

to me you are missusing the attribute of ID, Replace the ID for value: your option tag already have the id and name
<select name="SelCatName" class="TField" id="SelCatName">
your code will be:
<?php
$GetAllCategories = $con->query("SELECT * FROM categorie");
while ($ViewAllCategories = mysqli_fetch_array($GetAllCategories)){
?>
<option value="<?php echo $ViewAllCategories['catID']; ?>"> <?php echo $ViewAllCategories ['catName']; ?> </option>
<?php } ?>
Therefore you will find your post as only SelCatName = (numerical ID)
Now, if you need that the list of the catID and catName stores to the next page you can re-run your query in the next page and store them in an array.