Online toy shop entity-relationship diagram modeling a normalized relational schema with five core tables: CUSTOMERS, ORDERS, ORDER_ITEMS, PRODUCTS, and CATEGORIES. Data flows from customers placing orders, which reference order items linking to products, which belong to categories through foreign key relationships. This schema enforces referential integrity and eliminates data redundancy, essential for scalable e-commerce systems handling inventory, order fulfillment, and customer management. Fork this diagram on Diagrams.so to customize table structures, add indexes, or adapt it for your toy retail platform. The parent_id field in CATEGORIES enables hierarchical product organization—useful for nested toy subcategories like action figures > Marvel > Iron Man.