laravel 外键schema

        Schema::create(‘roles‘, function (Blueprint $table) {
            $table->tinyInteger(‘id‘)->unsigned()->autoIncrement();
            $table->string(‘name‘);
            $table->string(‘display_name‘);
        });

        Schema::create(‘permissions‘, function (Blueprint $table) {
            $table->smallIncrements(‘id‘);
            $table->string(‘name‘);
            $table->string(‘display_name‘);
        });

        Schema::create(‘permission_role‘, function (Blueprint $table) {
            $table->smallInteger(‘permission_id‘)->unsigned();
            $table->tinyInteger(‘role_id‘)->unsigned();
            $table->foreign(‘permission_id‘)->references(‘id‘)->on(‘permissions‘)->onDelete(‘cascade‘);
            $table->foreign(‘role_id‘)->references(‘id‘)->on(‘roles‘)->onDelete(‘cascade‘);
        });