30     protected $_smf_db_link = null;  variable in auth_plugin_authsmf20
225         if (!$this->_smf_db_link) {
226             $this->_smf_db_link = new mysqli(
232             if (!$this->_smf_db_link || $this->_smf_db_link->connect_error) {
235                 if ($this->_smf_db_link) {
236                     $error .= ' (' . $this->_smf_db_link->connect_errno . ')';
240                 $this->_smf_db_link = null;
246                 $this->_smf_db_link->set_charset('utf8');
249         return ($this->_smf_db_link && $this->_smf_db_link->ping());
257         if ($this->_smf_db_link !== null) {
258             $this->_smf_db_link->close();
259             $this->_smf_db_link = null;
280         $result = $this->_smf_db_link->query($query);
350             $user = $this->_smf_db_link->real_escape_string($user);
357             $result = $this->_smf_db_link->query($query);
422         $result = $this->_smf_db_link->query($query);