Entity relationship

Order model

Order model Four entities read left to right, referenced entity before referencing entity. A customer places zero or many orders; each order contains one or many order lines; each order line is priced by exactly one product, and a product may appear on zero or many order lines. Order is the anchor entity. Cardinality is written as text at both ends of every relationship. 1 places 0..* 1 contains 1..* 0..* priced by 1 Customer Table # customer_id uuid email text full_name text created_at date Order Table # order_id uuid placed_at date → customer_id Customer status text total_amount numeric OrderLine Table # order_id → Order # line_no int → product_id Product quantity int unit_price numeric Product Table # product_id uuid sku text name text list_price numeric Cardinality notation — 1 exactly one, 1..* one or many, 0..* zero or many; read at each end of a relationship. Markers — # primary key, → foreign key. OrderLine keeps its own attributes, so it is drawn as an entity rather than collapsed into a many-to-many line. Payment and shipment relationships are out of scope for this view.