Database Concepts - Data Warehouse Systems: Design and Implementation - page 20

Shippers Orders Employees

ShipperID
CompanyName
Phone

OrderID
CustomerID
EmployeeID
OrderDate
RequiredDate
ShippedDate (0,1)
ShipVia
Freight
ShipName
ShipAddress
ShipCity
ShipRegion (0,1)
ShipPostalCode (0,1)
ShipCountry

EmployeeID
FirstName
LastName
Title
TitleOfCourtesy
BirthDate
HireDate
Address
City
Region (0,1)
PostalCode
Country
HomePhone
Extension
Photo (0,1)
Notes (0,1)
PhotoPath (0,1)
ReportsTo (0,1)

Customers

CustomerID
CompanyName
ContactName
ContactTitle
Address
City
Region (0,1)
PostalCode (0,1)
Country
Phone
Fax (0,1)

OrderDetails

OrderID
ProductID
UnitPrice
Quantity
Discount

Suppliers

Employee
Territories
EmployeeID
TerritoryID

SupplierID
CompanyName
ContactName
ContactTitle
Address
City
Region (0,1)
PostalCode
Country
Phone
Fax (0,1)
Homepage (0,1)

Territories

Products

TerritoryID
TerritoryDescription
RegionID

ProductID
ProductName
QuantityPerUnit
UnitPrice
UnitsInStock
UnitsOnOrder
ReorderLevel
Discontinued
SupplierID
CategoryID

Regions

Categories

RegionID
RegionDescription

CategoryID
CategoryName
Description
Picture

Fig. 2.4 A relational schema that corresponds to the Northwind conceptual schema
in Fig. 2.1

some attributes of the relation Employees . In what follows, we use the notation
R.A to indicate the attribute A of relation R .
In the relational model, each attribute is defined over a domain ,or data
type , that is, a set of values with an associated set of operations, the most
typical ones are integer, float, date, and string. One important restriction of
the model is that attributes must be atomic and monovalued. Thus, complex