Home Backend Development PHP Tutorial 在php中作数据表必须有外键吗

在php中作数据表必须有外键吗

Jun 13, 2016 pm 12:21 PM
nbsp php sql workbench

在php中做数据表必须有外键吗
这个外键到底是啥,它是不是可有可无的,感觉很神秘的样子。看到很多高手都在指点菜鸟说要做一个外键,可是为啥要做的道理不说,就仙去也了,哎!只给鱼不授渔!
------解决思路----------------------
关系型数据库中,为了减少数据的冗余,把一些数据从主表中分离了出去,形成从表
指示主表和从表记录间的关系的字段,称为 关联键。广义的说,对从表而言这个键就是外键
数据库中所说的 外键,是指由数据库维护的关联键,从表中不能出现主表中没有的关联键值
显然这个外键的约束力是很强的,只用于一些条件苛刻的场合

所以结论是:外键不是必须的,盲目地设置外键会给系统的运行带来麻烦

------解决思路----------------------
实际开发中不建议使用外检,除非系统数据敏感,像支付系统等才会使用外键,Workbench 中如果设置了外键,生成sql的时候也会带上,不过建议生成sql的时候把外键去掉,做外键是为了帮助其他人理解你的数据库结构
------解决思路----------------------
不一定要有外键,看需求。
如果有触发器就用吧。

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