如何解决数据库关系中的循环问题？

Question

我有一个项目，用户可以在其中插入拍卖，招标和广告。他们还可以参加拍卖和招标。 我在设计和连接数据库及连接时遇到了麻烦。 我的数据库中的“关系”中存在循环。

我有六个表：

user(user_id,firstName,LastName,...) <-所有用户。

Order(order_id,user_id,OrderName,Desc,Amount,OrderType,...) <-所有广告。

Auction(auction_id,order_id,start_date,block_amount,min_increase,end_date,...)

Tender(tender_id,order_id,tender_base_amount,tender_start_date,tender_expire_date,...)

AuctionOffer(offer_auction_id,auction_id,user_id,auction_amount_offer,Date)

TenderOffer(tender_offer_id,tender_id,user_id,auction_amount_offer,Date)

我的关系：

您对解决此问题有何建议？

Answer 1

我看不到任何循环。所有外键都指向User。

CREATE TABLE [User] (
  [user_id] INT NOT NULL PRIMARY KEY,,
  [user_name] VARCHAR(50),
  [first_name] VARCHAR(50),
  [last_name] VARCHAR(50)
);

CREATE TABLE [Order] (
  [order_id] INT NOT NULL PRIMARY KEY,
  [user_id] INT REFERENCES [User] ( [user_id] )
  [order_name] VARCHAR(50)
);

CREATE TABLE [Auction] (
  [auction_id] INT NOT NULL PRIMARY KEY,
  [order_id] INT REFERENCES [Order] ( [order_id] )
  --,...
);

CREATE TABLE [AuctionOffer] (
  [offer_auction_id] INT NOT NULL PRIMARY KEY,
  [auction_id] INT REFERENCES [Auction] ( [auction_id] ),
  [user_id] INT REFERENCES [User] ( [user_id] )
  --,...
);

CREATE TABLE [Tender] (
  [tender_id] INT NOT NULL PRIMARY KEY,
  [order_id] INT REFERENCES [Order] ( [order_id] )
  --,...
);

CREATE TABLE [TenderOffer] (
  [tender_offer_id] INT NOT NULL PRIMARY KEY,
  [tender_id] INT REFERENCES [Tender] ( [tender_id] ),
  [user_id] INT REFERENCES [User] ( [user_id] )
  ---,...
);

必须首先创建

Users，然后创建Orders。之后，Tenders和TenderOffers或Auctions和AuctionOffers。

要在查询中联接表：

SELECT
    a.[auction_id],
    o.[order_id], o.[order_name], ou.[user_name] as [creator]
FROM [Auction] a
INNER JOIN [Order] o ON o.[order_id] = a.[order_id]
INNER JOIN [User] ou ON ou.[user_id] = o.[user_id]
;

SELECT
    aou.[user_name] as [bidder], ao.[created_date], ao.[auction_amount_offer]
FROM [AuctionOffer] ao
INNER JOIN [User] aou ON aou.[user_id] = ao.[user_id]
WHERE ao.[auction_id] = ?
ORDER BY ao.[Date] DESC
;

或组合：

SELECT
    a.[auction_id],
    o.[order_id], o.[order_name], ou.[user_name] AS [creator],
    aou.[user_name] AS [bidder], ao.[created_date], ao.[auction_amount_offer]
FROM [Auction] a
INNER JOIN [Order] o ON o.[order_id] = a.[order_id]
INNER JOIN [User] ou ON ou.[user_id] = o.[user_id]
LEFT JOIN [AuctionOffer] ao ON ao.[auction_id] = a.[auction_id] AND ao.[deleted_at] IS NULL
LEFT JOIN [User] aou ON aou.[user_id] = ao.[user_id]
ORDER BY a.[start_date], a.[start_time] a.[auction_id], ao.[created_at]

请注意，[User]有两个实例，但是别名不同。还有两列用于[User].[user_name]，但用于不同的表别名。

Answer 2

我同意马库斯的观点，我没有看到任何M：M（多对多）关系，1个用户可以有很多拍卖要价，投标要约和订单（1：M），1个订单可以有很多拍卖和招标（ 1：M）;并且1个拍卖或投标可以有许多拍卖要约或要约（1：M）。 TenderOffers和AuctionOffers表是解决任何M：M关系的“连接表”。