用TSQL定义SQL Server约束

IF OBJECT_ID('SalesHistory')>0
      DROP TABLE SalesHistory;

GO

IF OBJECT_ID('ProductTypes')>0
      DROP TABLE ProductTypes;

GO



CREATE TABLE ProductTypes

(
      ProductID SMALLINT, 
      ProductDescription VARCHAR(255), 
      CONSTRAINT pk_ProductID PRIMARY KEY (ProductID)

)

GO



CREATE TABLE [dbo].[SalesHistory](
      [SaleID] [int] IDENTITY(1,1) NOT NULL PRIMARY KEY,
      [ProductID] SMALLINT NULL,
      [SaleDate] [datetime] NULL,
      [SalePrice] [money] NULL--, 

CONSTRAINT fk_SalesHistoryProductID FOREIGN KEY (ProductID) REFERENCES ProductTypes(ProductID)

)

GO