Produktsuche nach Artikelnummer?

/* woocommerce sku search */
add_action('pre_get_posts', 'mmx_search_pre_get_posts');
function mmx_search_pre_get_posts( $q ){
	if ( is_search() ) {
		add_filter( 'posts_join', 'mmx_search_join' );
		add_filter( 'posts_where', 'mmx_search_where' );
	}
}
function mmx_search_join( $join = '' ){
	global $wp_the_query, $wpdb;
	if ( empty( $wp_the_query->query_vars['wc_query'] ) || empty( $wp_the_query->query_vars['s'] ) ) {
		return $join;
	}
	$join .= " INNER JOIN " . $wpdb->prefix . "postmeta AS mmx_meta ON ( " . $wpdb->prefix . "posts.ID = mmx_meta.post_id)";
	return $join;
}
function mmx_search_where( $where = '' ){
	global $wp_the_query;
	if ( empty( $wp_the_query->query_vars['wc_query'] ) || empty( $wp_the_query->query_vars['s'] ) ) {
		return $where;
	}
	$where = preg_replace( "/post_title LIKE ('%[^%]+%')/", "post_title LIKE $1 ) OR ( mmx_meta.meta_key = '_sku' AND CAST( mmx_meta.meta_value AS CHAR ) LIKE $1 ", $where );
	return $where;
}