如何把二维数组放到mysql中

$sql="select * from a";$result=$db->query($sql);while($row=mysql_fetch_array($result)){    $arr["id"][]=$row["id"];    $arr["no"][]=$row["no"];    $arr["name"][]=$row["name"];    }$sql2="select * from b";$result2=$db->query($sql2);while($row=mysql_fetch_array($result2)){    $arr2["id"][]=$row["id"];    $arr2["address"][]=$row["address"];}function array_diff_rewrite($array1, $array2){    //遍历$content中的key    foreach($array1 as $k=>$v)    {        //判断array2数组中是否有与array1中相同的key,不存在则赋予       if(!isset($array2[$k]))       {             $array2[$k]=$array1[$k];       }    }    return $array2;}$arr3=array_diff_rewrite($arr,$arr2);//print_r($arr3);function insert($array1,$array2){    foreach ($array1 as $k=>$v){    if(!isset($array2[$k]))            {                $sql4="alter table b add $k varchar(200)";            }}echo $sql4;}insert($arr3, $arr2);