mysqli多条查询语句执行出错

<?php

require_once ('connect.php');

$sql="select * from newsreport.news;";

$sql.="select id,username,age from user;";

$mysqli->multi_query($sql);

if($mysqli->multi_query($sql)){

    do{

        if($res=$mysqli->store_result()){ //use_result()或store_result()得到查询的结果集

            $rows[]=$res->fetch_all(MYSQLI_ASSOC);

            $res->free();

            //$res->free_result();

        }

    }while($mysqli->more_results()&&$mysqli->next_result());//more_result()检测是否有更多的结果集,next_result()将结果集指针向下移动一位

}else{

    echo $mysqli->error;

}

print_r($rows);

$mysqli->close();

?>

结果显示:

Commands out of sync; you can't run this command now