Get select information before submitting - ajax

Question

well i was reading around the solutions that stack-overflow was giving but i couldn't find the correct one... so here is my question:
Im creating a form with multiple selects ( not the select multiple="true" ) , no , i mean a form with lets say 4 different selects... retrieving data from a database so if i fill my first "select" lets say Style1 then i would like to get the "style1" selection so i can configure my second select query based on that and i can DISTINCT the values im looking for... i don't know if you get my idea, i've read i need to use AJAX but i couldn't figure out how to...
<form method="post">
<select name="category">
<?php $test = mysql_query("SELECT category FROM test_table GROUP BY category");
while($testing = mysql_fetch_array($test)){
echo "<option value=".$testing["category"].">".$testing["category"]."</option>";
}
?>
</select>
<select name="model">
<?php $test2 = mysql_query("SELECT model FROM test_table WHERE model = 'TRYING TO COMPARE WITH THE VALUE WITH THE FIRST SELECT' GROUP BY model");
while($testing2 = mysql_fetch_array($test2)){
echo "<option value=".$testing2["model"].">".$testing2["model"]."</option>";
</select>
</form>
Well that was just to get an idea, is not like the real one but its a pretty close example.
Sorry for my weird spelling
Thanks for your help !

Answer 1

<form method="post">
<select name="category" onchange="javascript:getDroupDownValues(this.value);">
<?php $test = mysql_query("SELECT category FROM test_table GROUP BY category");?>
<?php while($testing = mysql_fetch_array($test)):?>
<option value="<?php echo $testing["category"];?>"><?php echo $testing["category"];?></option>
<?php endwhile;?>
</select>
<div id="model-category">
</div>
</form>
<script type="text/javascript">
function getDroupDownValues(value)
{
jQuery.ajax({
dataType: "html",
type: "POST",
evalScripts: true,
url: 'your ajax url', // example your site url /ajax.php
data: ({category:value}),
success: function(data, textStatus) {
jQuery("#model-category").html(data);
}
});
}
</script>
Now in ajax.php script
<?php if(isset($_REQUEST['category']) && $_REQUEST['category']):?>
<select name="model">
<?php $test2 = mysql_query("SELECT model FROM test_table WHERE model = '{$_REQUEST['category']}' GROUP BY model");?>
<?php while($testing2 = mysql_fetch_array($test2)):?>
<option value="<?php echo $testing2["model"];?>"><?php echo $testing2["model"];?></option>
<?php endwhile;?>
</select>
<?php endif;?>