Fatal error: Call to a member function bind_param() on boolean

Question

I'm busy on a function that gets settings from a DB, and suddenly, I ran into this error:

Fatal error: Call to a member function bind_param() on boolean in C:\xampp2\htdocs\application\classes\class.functions.php on line 16

Normally, this would mean that I'm selecting stuff from unexisting tables and stuff. But in this case, I 'm not...

Here's the getSetting function:

public function getSetting($setting)
{
    $query = $this->db->conn->prepare('SELECT value, param FROM ws_settings WHERE name = ?');
    $query->bind_param('s', $setting);
    $query->execute();
    $query->bind_result($value, $param);
    $query->store_result();
    if ($query->num_rows() > 0)
    {
        while ($query->fetch()) 
        {
            return $value;
            if ($param === '1')
            {
                $this->tpl->createParameter($setting, $value);
            }
        }
    }
    else
    {
        __('invalid.setting.request', $setting);
    }
}

The $this->db variable is passed through a constructor. In case of need, here is it:

public function __construct($db, $data, $tpl)
{
    $this->db = $db;
    $this->tpl = $tpl;
    $this->data = $data;
    $this->data->setData('global', 'theme', $this->getSetting('theme'));
}

Also, since I'm making use of a database, my database connection:

class Database
{
    private $data;

    public function __construct($data)
    {
    $this->data = $data;
    $this->conn = new MySQLi(
      $this->data->getData('database', 'hostname'), 
      $this->data->getData('database', 'username'), 
      $this->data->getData('database', 'password'), 
      $this->data->getData('database', 'database')
    );
    if ($this->conn->errno)
    {
        __('failed.db.connection', $this->conn->errno);
    }
    date_default_timezone_set('Europe/Amsterdam');
}

I've already tested the connection, 100% positive that it works as intended. I'm setting the DB connection things in a configuration file:

'database' => array(
    'hostname' => '127.0.0.1',
    'username' => 'root',
    'password' => ******,
    'database' => 'wscript'
)

Now the weird thing is; the table exists, the requested setting exists, the DB exists, but still, that error won't leave. Here's some proof that the DB is correct:

Answer 1

The problem lies in:

$query = $this->db->conn->prepare('SELECT value, param FROM ws_settings WHERE name = ?');
$query->bind_param('s', $setting);

The prepare() method can return false and you should check for that. As for why it returns false, perhaps the table name or column names (in SELECT or WHERE clause) are not correct?

Also, consider use of something like $this->db->conn->error_list to examine errors that occurred parsing the SQL. (I'll occasionally echo the actual SQL statement strings and paste into phpMyAdmin to test, too, but there's definitely something failing there.)