public function query(){
  //新增數(shù)據(jù)
  //$bool = DB::table('wd_user')->insert(['username'=>'jack']);
  //dd($bool);
  //新增數(shù)據(jù)并且獲取到自增id
  //$id = DB::table('wd_user')->insertGetid(['username'=>'Tom']);
  //dd($id);
  //新增多條數(shù)據(jù)
  //$bool = DB::table('wd_user')->insert([['username'=>'a'],['username'=>'d']]);
  //dd($bool);
  //更新數(shù)據(jù)
  //$bool = DB::table('wd_user')->where('uid',7)->update(['username'=>'tom']);
  //dd($bool);
  //自增
  //$bool = DB::table('wd_user')->increment('age',1);
  //自減
  //$bool = DB::table('wd_user')->decrement('age',1);
  //自減并且更新數(shù)據(jù)
  //$bool = DB::table('wd_user')->decrement('age',1,['name'=>'imooc']);
  //刪除數(shù)據(jù)
  //$bool = DB::table('wd_user')->where('uid','>=',7)->delete();
  //dd($bool);
  //清空表
  //DB::table('wd_user')->truncate();
  //獲取數(shù)據(jù)
  //$user = DB::table('wd_user')->get();
  //dd($user);
  //數(shù)據(jù)排序
  //$user = DB::table('wd_user')->orderBy('uid','desc')->get();
  //dd($user);
  //增加查詢(xún)條件
  //$user = DB::table('wd_user')->where('uid','>=',5)->get();
  //dd($user);
  //增加多個(gè)查詢(xún)條件
  //$user = DB::table('wd_user')->where('uid > ? and age > ?',[5,18])->get();
  //dd($user);
  //查詢(xún)指定的字段
  //$user = DB::table('wd_user')->pluck('username');
  //dd($user);
  //查詢(xún)指定字段并以u(píng)id作為下標(biāo)
  //$user = DB::table('wd_user')->lists('username','uid');
  //dd($user);
  //查詢(xún)指定的一些字段
  //$user = DB::table('wd_user')->select('uid','username')->get();
  //dd($user);
  //分段查詢(xún)數(shù)據(jù)
  //DB::table('wd_user')->chunk(2,function($user){
    //var_dump($user);
  //});
  //統(tǒng)計(jì)記錄條數(shù)
  //$num = DB::table('wd_user')->count();
  //dd($num);
  //查詢(xún)最大值
  //$max = DB::table('wd_user')->max();
  //查詢(xún)最小值
  //$min = DB::table('wd_user')->min();
  //查詢(xún)平均數(shù)
  //$avg = DB::table('wd_user')->avg();
  //統(tǒng)計(jì)和值
  //$sum = DB::table('wd_user')->sum();
}