title: Convert strings into asterisks
body: <p>im working on a php-based system. one of its features is allows user to download an excel file containing all the information in one of my table in my database. my problem is, one data of that information is classified to other users. thus, i want to convert the output of that data into a string of asterisk.</p>
  
  <pre><code>&lt;?PHP
  
  
   //MySQL Database Connect
   include 'datalogin.php'; 
  
   function cleanData(&amp;$str)
   { 
   $str = preg_replace("/\t/", "\\t", $str); 
   $str = preg_replace("/\r?\n/", "\\n", $str); 
   if(strstr($str, '"')) $str = '"' . str_replace('"', '""', $str) . '"'; 
   }
   # filename for download 
  $filename = "website_data_" . date('Ymd') . ".xls"; 
   header("Content-Disposition: attachment; filename=\"$filename\""); 
   header("Content-Type: application/vnd.ms-excel");  
   $flag = false;
  
   //$result = pg_query("SELECT * FROM data_mapping ORDER BY CE_Hostname") or die('Query     failed!'); 
  /*$query = "SELECT * FROM data_mapping";
  
  while(false !== ($row = pg_fetch_assoc($result))) {  
  
  
  
  //while(false !== ($row = pg_fetch_assoc($result))) {  
  
  
  //$result=mysql_query($query);
  
  $row=mysql_fetch_array($result);
  $row=mysql_fetch_assoc ($result);
  
  
  //$row=$row['Cust_Segment'];
  // foreach($data as $row) 
  
   # display field/column names as first row
   if(!$flag) { 
   echo implode("\t", array_keys($row)) . "\r\n"; 
  
   $flag = true;  
   }
   array_walk($row, 'cleanData'); 
   echo implode("\t",($row)) . "\r\n";  
  
   }
   */
  
  
   $sql = 'SELECT CE_Hostname, Cust_Segment, Cust_Site_Name, CE_WAN_IP_Addr,     CE_Bkp_IP_Addr, Cust_Name, Svc_Type, com_string FROM data_mapping';
  
   $result = mysql_query($sql);
  
   if (!$result) {
      echo "DB Error, could not query the database&lt;br&gt;";
      echo 'MySQL Error: ' . mysql_error();
      exit;
      }
  echo "Hostname\t Group/System\t Site Name\t IP ADDR\t BKP IP ADDR\t System Name\t     Device Type\t Comm_String\r\n";
       while ($row = mysql_fetch_assoc($result)) {
      echo implode("\t",($row)) . "\r\n";  
      }
  
   mysql_free_result($result);
  
  
  //exit; 
  
   ?&gt;
  </code></pre>
  
  <p>i want to convert only the comm_string result. thanks.</p>