$con = mysqli_connect("localhost","root","","database");
function user_exists($username) {
$username = sanitize($username);
$query = "SELECT COUNT(user_id) FROM users WHERE username = '$username'";
$result = mysqli_query($con, $query);
return (mysql_result($result, 0) == 1) ? true : false;
}
我相信查询中存在错误，因为我总是收到"用户名被占用"错误，无论我是否插入现有用户名都没有关系。
**已解决，谢谢 **
试试这个
$query = "SELECT COUNT(user_id) as user_id FROM users WHERE `username` = '$username'";
$result = mysqli_query($con, $query);
mysql_result不会返回结果，它会发送错误，所以它总是给你真。
使用以下代码获取结果
$row = mysqli_fetch_array($result, MYSQLI_ASSOC);
if($row['user_id']){ return true; } else { return false; }