list/menu passing to another

[bcraig]

How do i get a list/menu to display records form DB depending on the selection on a previous list/menu?

 

The first list has main categories and  the second list has sub categories conected to the main

 

Heres a small example of my db table:

categoies

cat_id    |  parent_id  |  cat_name

    1                0            MainOne

    2                0            MainTwo

    3                1            SubOneA

    4                1            SubOneB

    5                2            SubTwoA

    6                2            SubTwoB

 

 

this is what i have for the first list

 

 

<?php
$mysqli = mysqli_connect("localhost", "root", "", "jobsnz");

if (mysqli_connect_errno()) {
printf("Connect failed: %s\n", mysqli_connect_error());
exit();
} else {

$sqlcat_drop = "SELECT cat_name FROM categories WHERE parent_id = 0";
$rescat_drop = mysqli_query($mysqli, $sqlcat_drop);
?>
<select name="categories">
<?php
if ($rescat_drop) {
	while ($newArray = mysqli_fetch_array($rescat_drop, MYSQLI_ASSOC)) {
		$catname  = $newArray['cat_name'];
		echo "<option>".$catname."</option>";
   	}
} else {
	printf("Could not retrieve records: %s\n", mysqli_error($mysqli));
}
?>	
</select>

[KrisNz]

1. Change your first query so that it gets the cat_id as well as the category name.

2. Change this

$catname  = $newArray['cat_name'];

echo "<option>".$catname."</option>";

 

to something like

 

$categoryId = $newArray['cat_id'];
echo "<option value="$categoryId">$catname</option>";

 

3. Set up a condition in the appropriate place to test if your categories drop down has been posted back. (I presume you've got that select inside a form that can be submitted!).

if (isset($_POST['categories']) and intval($_POST['categories']) > 0) {
    
   $parentId = intval($_POST['categories']);

  //run query to get records where parent_id = $parentId
// so if user chooses MainOne, $parentId = 1 and the resulting query should return records 3 & 4

}

4. display new records in much the same way you displayed the first set....

 

 

[bcraig]

this only brings the sub categories up after i post with a submit button. Is it possible for the main categories list to update the sub list instantly when a main category is selected? or is that beyond php?