Dropdown Filter mit Taxonomies

<form action="<?php bloginfo('url'); ?>" method="get">
        <p>Search for a manufacturer in the drop down menu:</p>
        <?php
        $taxonomies = array('manufacturer');
        $args = array('orderby'=>'name','hide_empty'=>true);
        $select = get_terms_dropdown($taxonomies, $args);
         
        $select = preg_replace("#<select([^>]*)>#", "<select$1 onchange='return this.form.submit()'>", $select);
        echo $select;
        ?>
        <noscript><div><input type="submit" value="Go" /></div></noscript>
        </form>
        </div>

function get_terms_dropdown($taxonomies, $args){
    $myterms = get_terms($taxonomies, $args);
    $output ="<select name='manufacturer'>";
    $output .="<option value='#'>Please select a manufacturer</option>";
    foreach($myterms as $term){
        $root_url = get_bloginfo('url');
        $term_taxonomy=$term->taxonomy;
        $term_slug=$term->slug;
        $term_name =$term->name;
        $link = $term_slug;
        $output .="<option value='".$link."'>".$term_name."</option>";
    }
    $output .="</select>";
    return $output;
    }

<?php
            $taxonomies = array('PGO');
            $select = test($taxonomies);
            echo $select;
        ?>






function test($taxonomies)
    
{
        global $wpdb;
        
        $result = $wpdb->get_results( "SELECT * FROM tbl_test WHERE hersteller = %h;", $taxonomies);    
        


        foreach ($result as $pointer) {
        
        $id = $pointer->id;
        
        $hersteller = $pointer->hersteller;
        $typ = $pointer->typ;
        
        echo $id." ".$hersteller." ".$typ."<br />";
        
        }  
    
}