public void createNtables() throws Exception{
		Connection conn = JDBC.createConnection();
		String table_name = "";
		for (int i=97;i<123;i++)
		{
			table_name = "n_gram_"+(char)i;
			String sql = " create table "+table_name+"(wordGroup varchar(100) primary key, wordAttribute varchar(100), frequence double(10,8), count int(10));";
			PreparedStatement stat = JDBC.getSatement(conn, sql);
			stat.executeUpdate();
			JDBC.close(stat);
		}
		JDBC.close(conn);
	}