PHP mysqli遍历表字段名和值

<?phpheader('Content-Type:text/html;Charset=utf-8');$db = new mysqli();$db->connect('localhost','root',12345,'test');$sql='select * from category';$query=$db->query($sql);while($rs=mysqli_fetch_array($query)){    $result[]=$rs;}$i=0;print_r($result);echo '<hr>';foreach($result as $key=>$value){    $i+=1;    if($i%2==0){    echo $key.' ';        echo $value.'<hr>';    }}$query->free();$db->close();