预防数据库攻击的正确做法 mysql_real_escape_string

<?phpfunction check_input($value){// 去除斜杠if (get_magic_quotes_gpc())  {  $value = stripslashes($value);  }// 如果不是数字则加引号if (!is_numeric($value))  {  $value = "'" . mysql_real_escape_string($value) . "'";  }return $value;}$con = mysql_connect("localhost", "hello", "321");if (!$con)  {  die('Could not connect: ' . mysql_error());  }// 进行安全的 SQL$user = check_input($_POST['user']);$pwd = check_input($_POST['pwd']);$sql = "SELECT * FROM users WHEREuser=$user AND password=$pwd";mysql_query($sql);mysql_close($con);?>