wpdb::db_version PHP Method

    public function db_version()
    {
        if ($this->use_mysqli) {
            $server_info = mysqli_get_server_info($this->dbh);
        } else {
            $server_info = mysql_get_server_info($this->dbh);
        }
        return preg_replace('/[^0-9.].*/', '', $server_info);
    }

 /**
  *	connectDatabase()
  *
  *	Initializes a connection to the mysql database.
  *	REQUIRES: databaseSettings portion of state to be set.
  *
  *	@return		boolean		True on success; else false. Success testing is very loose.
  */
 function connectDatabase()
 {
     $this->_before(__FUNCTION__);
     global $wpdb;
     $wpdb = new wpdb($this->_state['databaseSettings']['username'], $this->_state['databaseSettings']['password'], $this->_state['databaseSettings']['database'], $this->_state['databaseSettings']['server']);
     // See if we have a specified character set and collation to use from the source site.
     $charset = null;
     $collate = null;
     if (isset($this->_state['dat']['db_charset'])) {
         $charset = $this->_state['dat']['db_charset'];
     }
     if (isset($this->_state['dat']['db_collate'])) {
         $collate = $this->_state['dat']['db_collate'];
     }
     if (null !== $charset || null !== $collate) {
         pb_backupbuddy::status('details', 'Setting charset to `' . $charset . '` and collate to `' . $collate . '` based on source site.');
         $wpdb->set_charset($wpdb->dbh, $charset, $collate);
     } else {
         pb_backupbuddy::status('details', 'Charset nor collate are in DAT file. Using defaults for database connection.');
         pb_backupbuddy::status('details', 'Charset in wpdb: ' . $wpdb->charset);
     }
     // Warn if mysql versions are incompatible; eg importing a mysql < 5.1 version into a server running 5.1+.
     global $wpdb;
     if (isset($this->_state['dat']['db_version'])) {
         $incomingVersion = $this->_state['dat']['db_version'];
     }
     $thisVersion = $wpdb->db_version();
     pb_backupbuddy::status('details', 'Incoming mysql version: `' . $incomingVersion . '`. This server\'s mysql version: `' . $thisVersion . '`.');
     if (version_compare($incomingVersion, '5.1.0', '<') && version_compare($thisVersion, '5.1.0', '>=')) {
         pb_backupbuddy::status('warning', 'Error #7001: This server\'s mysql version, `' . $thisVersion . '` may have SQL query incompatibilities with the backup mysql version `' . $incomingVersion . '`. This may result in #9010 errors due to syntax of TYPE= changing to ENGINE=. If none occur you may ignore this error.');
     }
     return true;
 }