来自数组的PHP mysqli绑定参数

Question

我使用此函数将参数绑定到预准备语句中， 参数是$_POST["params"]内的字符串，看起来像是：

{type1:value1}{type2:value2}....

这个函数应该用语句绑定每个param，但是我得到错误：

function executeQuery($q)
 {
   global $server,$user,$pwd,$db,$output;
   $cn = mysqli_connect($server,$user,$pwd);
   mysqli_set_charset($cn,"utf8");
   mysqli_select_db($cn,$db);
   if(isset($_POST["params"]))
   {
    $ps = mysqli_prepare($cn,base64_decode($q));
    $params = $_POST["params"];
    $params_array = array();
    while(strlen($params)>0)
    {
        $n1 = strpos($params,"{");
        $n2 = strpos($params,"}'");

        $param = substr($params,$n1+1,$n2-($n1+1));
        $param_exploded = explode(":",$param);
        $type = $param_exploded[0];
        $params_array[$param_exploded [1]] = $param_exploded[1];
        mysqli_stmt_bind_param($ps,$type,$params_array[$param_exploded[1]]);
        if($n2+1>=strlen($params))
            break;
        $params = substr($params,$n2+1);
    }
    $ps->execute();
    $result = mysqli_stmt_result_metadata($ps);
    $count = mysqli_num_fields($result);
    $output.="<table><tr>"; 
   for($i =0;$i<$count;$i++)
   {
    $output.="<th>".mysqli_fetch_field_direct($result, $i)->name."</th>";
   }
  $output.="</tr>";
  while($row = mysqli_fetch_assoc($result))
  {
    $output.="<tr>";
    for($i =0;$i<$count;$i++)
    {
        $output.="<td>".$row[mysqli_fetch_field_direct($result,$i)->name].</td>";
    }
    $output.="</tr>";
  }
  $output.="</table>";
}

输出将是一个html表。 P.S：

查询

select * from t1 where c1 = ? and c2 = ?

$_POST["params"]的价值：

"{s:A}{s:N}"