Having trouble debugging a mysqli error

[k4]

Hey all,

  I'm having some trouble running some mysql statements through mysqli. I've tried to debug them various ways, but to no avail. This is the offending code:

class DBOPS {
protected $config, $mysqli;

public function __construct () {
$this->config = array (...snip...);
$this->mysqli = new mysqli ($this->config['server'], $this->config['username'], $this->config['password'], $this->config['database']);
session_start();
}

public function Login ($username, $password) {
$toreturn = NULL;

//Problem area is from here...

$encryptedpassword = hash(...snip...);

print_r(array(
$this->config['usertable']['username'],
$username,
$this->config['usertable']['password'],
$encryptedpassword));

$statement = $this->mysqli->stmt_init();
$statement->prepare('SELECT * FROM users WHERE ? = ? AND ? = ?');
$statement->bind_param(
'ssss',
$this->config['usertable']['username'],
$username,
$this->config['usertable']['password'],
$encryptedpassword);

$statement->execute();

print_r($statement->affected_rows);

//To here.

if ($statement->affected_rows == 1) {
$_SESSION[$this->config['sessiondata']['username']] = $username;
$_SESSION[$this->config['sessiondata']['lastactivity']] = time();

$toreturn = TRUE;
} else {
$toreturn = FALSE;
}

$statement->close();

return $toreturn;
}

 

The print_r($statement->affected_rows); statement always returns -1, which means a query error. Is there a problem with the syntax of the predefined query in $statement->prepare('SELECT * FROM users WHERE ? = ? AND ? = ?') ? I really can't seem to find the problem in this code. There are no errors returned. The output from the print_r() statements are

Array ( [0] => Name [1] => Trey [2] => Password [3] => ...snip... )

from the first print_r and

-1

from the second.

 

And lastly, I know that DIY login systems are generally discouraged, but this is more of a research project. I would greatly appreciate any help with this.

 

Thanks.

[PFMaBiSmAd]

affected_rows is only relevant for INSERT, UPDATE, or DELETE queries.

 

num_rows would be used with a SELECT query.

 

$statement->execute() returns either TRUE on success or FALSE on failure. You would probably want to test that to determine if the query produced an error or not and then $statement->error would tell you what the error was.