USE tempdb
GO
CREATE TABLE AuctionItems
(
itemid INT NOT NULL PRIMARY KEY NONCLUSTERED,
itemtype NVARCHAR(30) NOT NULL,
whenmade INT NOT NULL,
initialprice MONEY NOT NULL,
/* other columns */
)
--项目类型、项目的制造日期以及它的初始价格。只有与所有项目有关的属性被存储在AuctionItems
CREATE UNIQUE CLUSTERED INDEX idx_uc_itemtype_itemid
ON AuctionItems(itemtype, itemid)
INSERT INTO AuctionItems VALUES(1, N'Wine', 1822, 3000)
INSERT INTO AuctionItems VALUES(2, N'Wine', 1807, 500)
INSERT INTO AuctionItems VALUES(3, N'Chair', 1753, 800000)
INSERT INTO AuctionItems VALUES(4, N'Ring', -501, 1000000)
INSERT INTO AuctionItems VALUES(5, N'Painting', 1873, 8000000)
INSERT INTO AuctionItems VALUES(6, N'Painting', 1889, 8000000)
--其他属性特定于项目类型，并且不同类型的新项目被不断地添加。这样的属性可以存储在不同的ItemAttributes 表中，其中每个项属性都存储在不同的行中。每个行都包含项目ID、属性名称和属性值
CREATE TABLE ItemAttributes
(
itemid INT NOT NULL REFERENCES AuctionItems,
attribute NVARCHAR(30) NOT NULL,
value SQL_VARIANT NOT NULL,
PRIMARY KEY (itemid, attribute)
)
INSERT INTO ItemAttributes
VALUES(1, N'manufacturer', CAST(N'ABC' AS NVARCHAR(30)))
INSERT INTO ItemAttributes
VALUES(1, N'type',
