thinkphp5隨機查詢數據

$num = 5;//需要抽取的默認條數
$countcus = db(表名)->count();//獲取總記錄數
$min = db(表名)->min(字段名);//統計某個字段最小數據
$max = db(表名)->max(字段名);//統計某個字段最大數據
 if($countcus<$num){
         $num = $countcus;
}
$i = 1;
$flag = 0;
 $ary = array();
while($i<=$num){
        $rundnum = rand($min,$max);//抽取隨機數
        if($flag != $rundnum){
                 //過濾重複
                if(!in_array($rundnum,$ary)){
                        $ary[] = $rundnum;
                        $flag = $rundnum;
                }else{
                       $i--;
               }
            $i++;
      }
}
$res = db(表名)->where('字段名','in',$ary,'or')->select();