มีปัญหา Error functions ช่วยแก้ไขหน่อยครับ .. Warning: Missing argument 2 for wpdb::prepare(), called in

// get image id
// retrieves the attachment ID from the file URL
function get_image_id($image_url) {
	global $wpdb;
	$prefix = $wpdb->prefix;
	$attachment = $wpdb->get_col($wpdb->prepare("SELECT ID FROM " . $prefix . "posts" . " WHERE guid='" . $image_url . "';"));  // บรรทัด 160 ที่มีปัญหาครับ
	return $attachment[0];
}

function comment_list( $comment, $args, $depth ) {
	$GLOBALS['comment'] = $comment;
	switch ( $comment->comment_type ) :
		case 'pingback' :
		case 'trackback' :
	?>

function prepare( $query, $args ) {  // บรรทัด 990 ที่มีปัญหาครับ
		if ( is_null( $query ) )
			return;

		$args = func_get_args();
		array_shift( $args );
		// If args were passed as an array (as in vsprintf), move them up
		if ( isset( $args[0] ) && is_array($args[0]) )
			$args = $args[0];
		$query = str_replace( "'%s'", '%s', $query ); // in case someone mistakenly already singlequoted it
		$query = str_replace( '"%s"', '%s', $query ); // doublequote unquoting
		$query = preg_replace( '|(?<!%)%f|' , '%F', $query ); // Force floats to be locale unaware
		$query = preg_replace( '|(?<!%)%s|', "'%s'", $query ); // quote the strings, avoiding escaped strings like %%s
		array_walk( $args, array( $this, 'escape_by_ref' ) );
		return @vsprintf( $query, $args );
	}