当主表更新时，外键是否自动更新？ [英] Does the foreign keys automatically get updated as primary table is updated?

问题描述

以上是我的简单的数据库设计，只是想获得有关事情发生的信息，因为我真的是数据库的新手。以下是我的问题：

1. 当我在wall表中更新wall_id时，wall_categories表中的wall_id是否也会更新？作为
   中的wall_id wall_categories表指向wall表中的wall_id。
   

2. 与walls表中的desktop_id相同，因为它是引用desktop_id的外键在desktop_wall表中，所以当我更新
   桌面desktop_id在桌面桌面desktop_id deskotp_wall也
   得到更新？




3. 如果它没有更新默认情况下，如何做到这一点？

非常感谢！

解决方案

此功能称为级联参照完整性。定义外键约束时是可选的。在这里描述启用它的语法（Micorosoft SQL，但语法是标准的，大多数DBMS支持它）： .com / en-us / library / ms186973（v = sql.105）.aspxrel =nofollow> http://technet.microsoft.com/en-us/library/ms186973（v = sql.105） .aspx

Above is my simple database design, just wanted to gain information about how things happen as I'm really new at database. Following are my questions:

1. as I update wall_id in walls table, does the wall_id in wall_categories table also get updated? as the wall_id in wall_categories table references to wall_id in walls table.

2. same with desktop_id in walls table since it is a foreign key referencing to desktop_id in desktop_wall table, so when I update desktop_id in walls table does the desktop_id in deskotp_wall also gets updated?

3. if it does not update by default, how can this be done?

Thanks a lot!

解决方案

This feature is called cascading referential integrity. It's optional when you define a foreign key constraint. The syntax to enable it is described here (Micorosoft SQL but the syntax is standard and most DBMSs support it):

http://technet.microsoft.com/en-us/library/ms186973(v=sql.105).aspx

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