A brief analysis of php filtering html string to prevent SQL injection

Batch filtering post,get sensitive data

$_GET = stripslashes_array($_GET);
$_POST = stripslashes_array($_POST);

Data filtering function

function stripslashes_array(&$array) {
 while(list($key,$var) = each($array)) {
  if ($key != 'argc' && $key != 'argv' && (strtoupper($key) != $key || ''.intval($key) == "$key")) {
   if (is_string($var)) {
    $array[$key] = stripslashes($var);
   }
   if (is_array($var))  {
    $array[$key] = stripslashes_array($var);
   }
  }
 }
 return $array; 
}

Replace HTML tail tag for filtering service

function lib_replace_end_tag($str)
{
 if (empty($str)) return false;
 $str = htmlspecialchars($str);
 $str = str_replace( '/', "", $str);
 $str = str_replace("\\", "", $str);
 $str = str_replace(">", "", $str);
 $str = str_replace("<", "", $str);
 $str = str_replace("<SCRIPT>", "", $str);
 $str = str_replace("</SCRIPT>", "", $str);
 $str = str_replace("<script>", "", $str);
 $str = str_replace("</script>", "", $str);
 $str=str_replace("select","select",$str);
 $str=str_replace("join","join",$str);
 $str=str_replace("union","union",$str);
 $str=str_replace("where","where",$str);
 $str=str_replace("insert","insert",$str);
 $str=str_replace("delete","delete",$str);
 $str=str_replace("update","update",$str);
 $str=str_replace("like","like",$str);
 $str=str_replace("drop","drop",$str);
 $str=str_replace("create","create",$str);
 $str=str_replace("modify","modify",$str);
 $str=str_replace("rename","rename",$str);
 $str=str_replace("alter","alter",$str);
 $str=str_replace("cas","cast",$str);
 $str=str_replace("&","&",$str);
 $str=str_replace(">",">",$str);
 $str=str_replace("<","<",$str);
 $str=str_replace(" ",chr(32),$str);
 $str=str_replace(" ",chr(9),$str);
 $str=str_replace("    ",chr(9),$str);
 $str=str_replace("&",chr(34),$str);
 $str=str_replace("'",chr(39),$str);
 $str=str_replace("<br />",chr(13),$str);
 $str=str_replace("''","'",$str);
 $str=str_replace("css","'",$str);
 $str=str_replace("CSS","'",$str); 
 return $str;  
}