//获取指定多行多列，二维,,对象 【select】

         $names = '';

         $names = DB::table('student')->whereRaw('id > ? and age < ?',[,])->select('id','name','age')->get();

         var_dump($names);

         echo "<br>";

        //获取指定单行，一维,,对象 【find】

        $names = '';

        $names = DB::table('student')->whereRaw('id > ? and age < ?',[,])->select('id','name','age')->first();

        var_dump($names);

        echo "ceshi";

        echo "<br>";

        //获取指定列值，返回字符串【getField】

        $names = DB::table('student')->whereRaw('id >= ? and age < ?',[,])->value('name');

        var_dump($names);   //  string(3) "bob"

        echo "<br>";

        //获取指定name单列，返回一维数组【getField,true】

        $names = '';

        $names = DB::table('student')->whereRaw('id >= ? and age < ?',[,])->pluck('name');

        var_dump($names);

        echo "<br>";

        var_dump(json_encode($names,true));//  array "["Alice"]"