Question

我怀疑这两种方法中哪种方法更有效，

让我们假设我有一个针对每个用户的数据库，每个用户可能有很多商店，所以我有一个表CONFIG，其中包含诸如SHOP_CONFIG（商店的编号）和POS_CONFIG（ POS的ID）一家商店可以拥有多个POS 。

然后我有一个带有ITEMS的表，这些表属于属于ID_ITEMS DESC_ITEMS等列的商店，每个POS中的每个SHOP的项目都可以相同，或者每个POS可以具有不同的ITEMS。所以现在我必须查看每个SHOP / POS

的所有项目

所以我的疑问是：

我应该在ID上添加CONFIG，然后用SHOP_ITEMS的{{1}}作为外键，用{{1 }}作为外键？

还是我可以将ID和CONFIG列添加到ID_ITEMS表中？

（表SHOP仍用于其他目的）

Answer 1

一个更长的例子，但是您可以根据您的项目进行调整。

-- Shop owner (user) OWN exists.
--
owner {OWN}
   PK {OWN}

-- Owner OWN owns shop number SHP# (of that owner).
--
shop {OWN, SHP#}
  PK {OWN, SHP#}

FK {OWN} REFERENCES owner {OWN}

-- Point of sale number POS#,
-- of shop number SHP#, of owner OWN exists.
--
point_of_sale {OWN, SHP#, POS#}
           PK {OWN, SHP#, POS#}

FK {OWN, SHP#} REFERENCES shop {OWN, SHP#}

-- Item ITM exists.
--
item {ITM}
  PK {ITM}

-- Item ITM is available in shop
-- number SHP#, of owner OWN.
--
item_shop {ITM, OWN, SHP#}
       PK {ITM, OWN, SHP#}

FK1 {ITM} REFERENCES item {ITM}

FK2 {OWN, SHP#} REFERENCES shop {OWN, SHP#}

-- On DTE (date-time), item ITM was sold in
-- quantity QTY, thru point of sale number POS#,
-- of shop number SHP#, of owner OWN.
--
sales {OWN, SHP#, POS#, DTE, ITM, QTY}
   PK {OWN, SHP#, POS#, DTE, ITM}

      FK1 {ITM, OWN, SHP#} REFERENCES
item_shop {ITM, OWN, SHP#}

          FK2 {OWN, SHP#, POS#} REFERENCES
point_of_sale {OWN, SHP#, POS#}

注意：

All attributes (columns) NOT NULL

PK = Primary Key
FK = Foreign Key

Using suffix # to save on screen space.
OK for SQL Server and Oracle, for others use _NO.
For example, rename SHP# to SHP_NO.

多对多桌子还是一张桌子？

1 个答案: