在php中作数据表必须有外键吗
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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