• Categories:产品类别；
• Customers：客户；
• Employees:雇员
• Employees Territories:员工涉及领域
• Order Details：订单明细
• Orders：订单
• Products：产品
• Region：地区
• Shippers：运货商
• Suppliers：供应商
• Territories：地域

        在NorthWind数据库中创建关系图：
        下面进行几次查询了解数据内容：

select productid,productname,unitprice from Products
where UnitPrice>49

查询结果：

select productid,productname,UnitsInStock,UnitsOnOrder
 from Products where UnitsInStock<UnitsOnOrder

查询结果：

select * from Products
where ProductName='Aniseed Syrup' or ProductName='Ipoh Coffee'

select * from Products
where ProductName in('Aniseed Syrup','Ipoh Coffee')

查询结果：

select * from Products
where SupplierID=CategoryID

查询结果：

select SupplierID,CompanyName,Phone,Fax from Suppliers
where Phone is not null and fax is null

select * from Suppliers
order by City  desc

select SupplierID,CompanyName,Country from Suppliers
where Country in('USA','UK','Germany')

select SupplierID,CompanyName,ContactTitle,Phone 
from Suppliers
where  ContactTitle='Marketing Manager' and Phone is not null

select distinct ShipVia from Orders

select distinct ShipCity from Orders

select OrderID,ShippedDate,RequiredDate from Orders
where ShippedDate>RequiredDate

select OrderID,CustomerID,Freight from Orders
where Freight<55

select * from Categories
where CategoryName like '_e%'

select * from Categories
where Description like '%sweet%'