Foreign Key - ERDL Diagram Syntax
- Type FK to mark a field as foreign key
- To define a composite foreign key, use the table level FK() syntax
Order
-
OrderID int PK
CustomerID int FK > Customer.CustomerID
TotalAmount money NOT NULL
OrderStatusID int
(or)
Order
-
OrderID int PK
CustomerID int
TotalAmount money NOT NULL
OrderStatusID int
FK(CustomerID,OrderID) > OrderDetail(CustomerID,OrderID)
Relationships:
- < one-to-many. e.g: Customer.id < Order.Id
- > many-to-one. e.g: Order.Id > Customer.id
- - one-to-one. e.g: Customer.id - Address.id
- <> many-to-many. e.g: authors.id <> books.id
NOTE: All table names and column names are case sensitive. Ensure to use the same case during FK references
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