Can't execute query

			SELECT 
				C2.name,
				C2.id,
				C2.url,
				C2.lft,
				C2.rgt
			FROM 
				categories_horiz AS C1,
				categories_horiz AS C2
			WHERE 
				C1.id = ''
				AND
				C2.lft <= C1.lft
				AND
				C2.rgt >= C1.rgt
			ORDER BY 
				C2.lft ASC
			

MySQL Error:

This script cannot continue, terminating.