我有两种资源,砖块和墙壁。class Brick extends Model public function walls() return $this->belongsToMany('App\Wall')->withTimestamps();}class Wall extends Model public function bricks() return $this->hasMany('App\Brick'
我有一个关于约束的一般性问题。下面的例子有什么区别? OrderID int NOT NULL PRIMARY KEY, PersonID int FOREIGN KEY REFERENCES Persons(PersonID) OrderID int NOT NULL, PersonID int,
PRIMARY KEY (OrderID)