连接数据库失败

Question

I can't seem to figure out the problem with my database or the connection to it. I get this error when I try to run it.

Notice: Trying to get property of non-object in /Applications/XAMPP/xamppfiles/htdocs/swiftappandmysql/db/MySQLDAO.php on line 54

AND

Fatal error: Uncaught exception 'Exception' in /Applications/XAMPP/xamppfiles/htdocs/swiftappandmysql/db/MySQLDAO.php:53 Stack trace: #0 /Applications/XAMPP/xamppfiles/htdocs/swiftappandmysql/scripts/registerUser.php(41): MySQLDAO->registerUser('email', 'aske', 'meyer', '1bf528e7f15d11c...', 'KO\x8E\xD0\xCE/\xBD\xACK\xD1d\x18\x9A\x07\xE1...') #1 {main} thrown in /Applications/XAMPP/xamppfiles/htdocs/swiftappandmysql/db/MySQLDAO.php on line 53

Connection file:

<?php class Conn { public static $dbhost = "localhost";
        public static $dbuser = "root";
        public static $dbpass = "";
        public static $dbname = "app";} ?>

MySQL file:

public function registerUser($email, $first_name, $last_name, $password, $salt)
{ 
    $sql = "insert into users set email=?, first_name=?, last_name=?, user_password=?, salt=?";
    $statement = $this->conn->prepare($sql);
    if (!$statement)
      throw new Exception($statement->error);
    $statement->bind_param("sssss", $email, $first_name, $last_name, $password, $salt);
    $returnValue = $statement->execute();
    return $returnValue;  
}   

This is line 54. if (!$statement) throw new Exception($statement->error);

Answer 1

The if() block runs when $statement = FALSE, so $statement->error can't possibly be right. The error property is in $this->conn, so it should be

if (!$statement) {
    throw new Exception($this->conn->error);
}

Then the error message will show the problem with your SQL.