如果我不了解我按记录居住的领域的数量,那么我应如何建立我的数据库/表格?
例如,如果我有一个网络形式,使用户能够进入他拥有的所有汽车,而且我不想将他限制在一定数目之内,那么我如何在数据库中储存这一点?
以上问题涉及类似情况,如储存用户订单(每批物品数量不变)。
相反,在相关数据库管理系统中,你在与上级实体(用户)联系的附属表格中制作儿童记录。 有一个称为数据库热化>的概念,目标是每个表格都包含单一类型的实体的数据。
因此,有<条码>用户。 用户信息表:
user_id | user_name | email | ...
1234 | User1 | user1@example.com | ...
2356 | User2 | user2@example.com | ...
接下来是一份储存用户每辆汽车信息的表格:
user_car_id | user_id | car_label | make | model | ...
1 | 1234 | MyCar | Ford | 2011 | ...
2 | 2356 | A Car | Chevrolet | 2010 | ...
3 | 1234 | MyOtherCar| BMW | 2000 | ...
因此,不要在<条码>用户上储存汽车的内装。 表1. 按<代码>用户_id栏列出的与每个用户有关的信息。 这是一种单人关系的例子,在这种关系中,用户可以拥有许多相关的汽车。
这是一个完整的议题:数据库的正常化。
答案很短,你的发言不止一个。
在你的例子中,你有一张个人桌子、一张汽车桌和一个把人与汽车联系起来的第三张汽车。
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