我正在使用 json 向使用 php 的 ios 应用程序提供数据。但是在浏览器中运行代码时，它显示服务器错误。如果数据库中没有值，则显示{"posts":null} 为代码中提供的。但是如果数据库中有值，就会出现问题。它显示错误
Server error
The website encountered an error while retrieving http://path to the server file/php/categoryitemlisting.php?category=11. It may be down for maintenance or configured incorrectly.
Here are some suggestions:
Reload this webpage later.
HTTP Error 500 (Internal Server Error): An unexpected condition was encountered while the server was attempting to fulfill the request.
此错误仅针对此 php 文件发生。使用其他文件，我可以传输数据。
我的 connection.php 文件：
<?php
$link = mysql_connect("127.0.0.1","root","") or die('Cannot connect to the DB');
mysql_set_charset("utf8");
mysql_select_db('cotton',$link) or die('Cannot select the DB');
?>
Categoryitemlisting.php
<?php
require('connection.php');
$item = array() ;
/* connect to the db */
if(isset($_REQUEST['category']))
{
$k=$_REQUEST['category'];
/* grab the posts from the db */
// $k=11;
$catid = mysql_query("SELECT entity_id FROM field_data_field_cat WHERE field_cat_tid= $k");
while($r = mysql_fetch_assoc($catid))
{
$category[] = $r['entity_id'];
foreach ( $category as $cat );
{
$data= mysql_query("SELECT field_data_field_name.entity_id, field_data_field_name.field_name_value, file_managed.uri, field_data_field_sec.field_sec_tid FROM file_managed INNER JOIN ( field_data_field_thumb, field_data_field_name, field_data_field_sec ) ON ( file_managed.fid = field_data_field_thumb.field_thumb_fid AND field_data_field_name.entity_id = field_data_field_thumb.entity_id AND field_data_field_thumb.entity_id = field_data_field_sec.entity_id ) WHERE field_data_field_name.entity_id = $cat");
$items = mysql_fetch_assoc($data);
$item[]= $items;
}
}
$re="public:\/\/";
$list = json_encode(array('posts'=>$item));
$list = str_replace( $re, "http://localhost/sites/default/files/" ,$list);
echo $list;
@mysql_close($link);
}
else
{
echo "connection failed";
}
?>
如何通过修复此错误来获取值？我不认为这是服务器的问题。如果代码中还有其他错误？