Question

i have a drop down list populated with values from database. What i am trying to achieve is assign a select statement to each value.

Populate menu code

<?php
require 'conn.php';

$filter=mysql_query("select distinct fuel_type from car");
while($row = mysql_fetch_array($filter)) {
$options .="<option>" . $row['fuel_type'] . "</option>";

$menu="<form id='filter' name='filter' method='post' action=''>
  <p><label>Filter</label></p>
    <select name='filter' id='filter'>
      " . $options . "
    </select>
</form>";
}
echo $menu;
?>

Now this menu will be used to filter out car listing and will be placed on the sidebar

How can i assign each value from the drop down list a different select statement like;
select * from car where fuel_type = (dropdown list value selected) without having to submit the form.

perhaps something like the following?

    if($_GET["filter"] == 'Petrol'){
$query=mysql_query("select * from car where fuel_type = 'Petrol'");
header("Location: cars.php");
}

Answer 1

First, when you’re building your option tag, assign the value that you’d like to filter on in the SQL query to the value attribute:

$options .="<option value='".$row['fuel_type']."'>" . $row['fuel_type'] . "</option>";

Second, assign unique ID’s to your form and your select element. Then assign the form submit action to the select elements onchange event.

$menu="<form id='filterForm' name='filterForm' method='post' action=''>
  <p><label>Filter</label></p>
    <select name='filter' id='filter' onchange='document.getElementById("filterForm").submit()'>
      " . $options . "
    </select>
</form>";
}

Now when you change the select option, the form will be submitted and the option value that is selected will be populated as that value of the select element #filter.

On the php page that your form posts to, check for the value of the select element with the id #filter to build the query.