public boolean hasPreferredDatabase() {
        return this.config.hasOption(ClickHouseClientOption.DATABASE);
    }
Checks if preferred database was specified or not. When preferred database
was not specified, {@link #getDatabase()} will return default database.

@return true if preferred database was specified; false otherwise
clickhouse-client/src/main/java/com/clickhouse/client/ClickHouseNode.java