The figure illustrates the E-R diagram for the purchase order application. The main entities are Customer
, Purchase Order
, Line Item
, and Stock Item
. The Customer
entity has a one-to-many relationship with Purchase Order
. The Purchase Order
entity has a many-to-many relationship with Stock Item
and a one-to-many relationship with Line Item
. The Line Item
entitiy has a many-to-one relationship with Stock Item
.