What is Foreign key and how to create a Foreign key constraint? Note:Foreign Keys are used to enforce(强制) database integrity(完整) . In layman's terms(一般来说), A foreign key in one table points to a primary key in another table. The foreign key constrain…
http://highscalability.com/blog/2016/1/25/design-of-a-modern-cache.html MONDAY, JANUARY 25, 2016 AT 8:56AM This is a guest post by Benjamin Manes, who did engineery things for Google and is now doing engineery things for a new load documentation star…
AS- This view is not constrained vertically. At runtime it will jump to the left/(0,0) unless you add constraint. 呐,design 拖拽按钮呀文字框过去的时候,text状态会出现的红色警告,说没有添加约束,运行时会跳到(0,0)左上角位置喔 然后呢,design状态下拖过去之后呢,在这小道具右键,Constraint(约束) Layout->Infer Constraints,点一…