php - mysql 查询到 mysqli 查询

Question

您好，我想将以下代码迁移到 mysqli。请帮忙，这是登录功能。第一个函数获取 user_id从数据库中，而第二个函数检查 username 是否和password匹配 user_id 中的该用户.

function user_id_from_usernam­e($username){
   $username = sanitize($username);
   return mysql_result(mysql_query("SELECT `user_id` FROM `users` WHERE `username` = '$username'"), 0, 'user_id');
}

function login($username, $password){
  $user_id = user_id_from_username($username);
  $username = sanitize($username);
  $password = md5($password);
  $query = mysql_query("SELECT COUNT(`user_id`) FROM `users` WHERE `username` = '$username' AND `password` = '$password'");
  return  ( mysql_result($query­, 0) == 1)? $user_id : false;
}

Answer 1

mysqli_query 的正确查询形式是:

mysqli_query($connection_variable,"SELECT COUNT(`user_id`) FROM `users` WHERE `username` = '$username' AND `password` = '$password'");