General Structure A B1 B2 Ck A parent may have an arrow pointing to a child,but a child must have an arrow pointing to its parent. Database System Concepts,5th Ed. B.4 ©Silberschat乜，Korth and SudarshanDatabase System Concepts, 5 B.4 ©Silberschatz, Korth and Sudarshan th Ed. General Structure A parent may have an arrow pointing to a child, but a child must have an arrow pointing to its parent