Get attachment ID/Size from url

snippet-wp-get-attachment-id-size.php

//Return the attachment ID of an image
function get_attachment_id_from_src ($image_src) {

	global $wpdb;
	$query 	= "SELECT ID FROM {$wpdb->posts} WHERE guid='$image_src'";
	$id 	= $wpdb->get_var($query);
	return $id;

}

//Gets an image thumbnail from attachment ID
function get_attachment_image_size_from_src( $url, $size = 'large' ){
	$image_id 		= get_attachment_id_from_src( $url );
	$image_object 	= wp_get_attachment_image_src( $image_id, $size );
	return $image_object[0];
}