private void createTables() {
		try {
			Statement stmt = conn.createStatement();
			
			// !!!!!
			// please comment these 2 lines below for the first time execution,
			// and then uncomment them for the future use
			stmt.execute("DROP TABLE words");
			stmt.execute("DROP TABLE batches");
			// please comment these 2 lines above for the first time execution,
			// and then uncomment them for the future use
			// !!!!!
			
			stmt.execute("CREATE TABLE batches ( " + "id INT NOT NULL, "
					+ "maxTime BIGINT, " + "minTime BIGINT, "
					+ "avgTime BIGINT, " + "PRIMARY KEY (id) )");

			stmt.execute("CREATE TABLE words ( " + "word VARCHAR(20), "
					+ "process_time BIGINT, " + "parity BOOLEAN, "
					+ "batch_id INT, "
					+ "FOREIGN KEY (batch_id) REFERENCES batches)");
		} catch (SQLException sqlExcept) {
			sqlExcept.printStackTrace();
		}
	}