Article 是模型的名
1、统计数据条数: Article::where("id",">",5) -> count();
2、获取最大值: Article::where("id",">",5) -> max('num');
3、获取最小值: Article::where("id",">",5) -> min('num');
4、求和: Article::where("id",">",5) -> sum('num');
5、求平均值: Article::where("id",">",5) -> avg('num');