Can Spring, JdbcTemplate not use Columns not specified in the Select List?

Question

I'm learning spring.

I can execute this query fine in MySQL (of course):

SELECT notes, month(dt) month, dayofmonth(dt) day, hour(dt) hour, minute(dt) minute, 
avg(temperature2) temperature2, avg(temperature) temperature, avg(temperature1) temperature1
FROM temperature WHERE dt > curdate() - 1 
GROUP BY notes, month(dt), dayofmonth(dt), hour(dt), minute(dt)
ORDER BY dt DESC

Python can do this fine.

Just using plain old Jdbc works:

Connection conn = null ;

    try {
        System.out.println("Start try");
        String driver = "com.mysql.jdbc.Driver";

        Class.forName(driver).newInstance();

        conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/brew", "root", "");

        String sql = "SELECT notes, month(dt) month, dayofmonth(dt) day, hour(dt) hour, "
                + "minute(dt) minute, avg(temperature2) temperature2, avg(temperature) temperature, "
                + "avg(temperature1) temperature1, "
                + "FROM temperature WHERE dt > curdate() - 1 "
                + "GROUP BY notes, month(dt), dayofmonth(dt), hour(dt), minute(dt) "
                + "ORDER BY dt DESC ";

        PreparedStatement ps = conn.prepareStatement(sql) ;

        ResultSet rs = ps.executeQuery();

        if (rs.next()) {
            System.out.println(rs.getString("notes") + " " + rs.getDouble("temperature"));
        } else {
            System.out.println("No results");
        }

        rs.close();

        ps.close();

But not JdbcTemplate in Spring?

public List<Temperature> getMinutelyTemperatures() {
    String sql = "SELECT notes, month(dt) month, dayofmonth(dt) day, hour(dt) hour, "
            + "minute(dt) minute, avg(temperature2) temperature2, avg(temperature) temperature, "
            + "avg(temperature1) temperature1, "
            + "FROM temperature WHERE dt > curdate() - 1 "
            + "GROUP BY notes, month(dt), dayofmonth(dt), hour(dt), minute(dt) "
            + "ORDER BY dt DESC ";
    //return namedParameterJdbcTemplate.query(sql, new MapSqlParameterSource(), new TemperatureMapper());
    return jdbcTemplate.query(sql, new TemperatureMapper());
}
private static final class TemperatureMapper implements RowMapper<Temperature> {
    @Override
    public Temperature mapRow(ResultSet resultSet, int rowNum) throws SQLException {
        Temperature temperature = new Temperature();
        temperature.setNotes(resultSet.getString("notes"));
        temperature.setDt(resultSet.getDate("dt"));
        temperature.setTemperature(resultSet.getDouble("temperature"));
        temperature.setTemperature1(resultSet.getDouble("temperature1"));
        temperature.setTemperature2(resultSet.getDouble("temperature2"));
        return temperature;
    }
}

And I can't even use a column from a subquery to order on ?

public List<Temperature> getMinutelyTemperatures() {    
    String sql = "SELECT notes, month(dt) month, dayofmonth(dt) day, hour(dt) hour, "
            + "minute(dt) minute, avg(temperature2) temperature2, avg(temperature) temperature, "
            + "avg(temperature1) temperature1 "
            + "FROM (SELECT notes, dt, temperature2, temperature, temperature1 FROM temperature WHERE dt > curdate() - 1) b "
            + "GROUP BY notes, month(dt), dayofmonth(dt), hour(dt), minute(dt) "
            + "ORDER BY b.dt DESC ";
    //return namedParameterJdbcTemplate.query(sql, new MapSqlParameterSource(), new TemperatureMapper());
    return jdbcTemplate.query(sql, new TemperatureMapper());
} 

What am I overlooking here?

Here is the error:

nested exception is java.sql.SQLException: Column 'dt' not found.

If I just remove it from the order by clause, or just remove it from the where clause, I receive the same error.

Answer 1

Your select statement

SELECT notes, month(dt) month, dayofmonth(dt) day, hour(dt) hour, minute(dt) minute, 
avg(temperature2) temperature2, avg(temperature) temperature, avg(temperature1) temperature1
FROM temperature WHERE dt > curdate() - 1 
GROUP BY notes, month(dt), dayofmonth(dt), hour(dt), minute(dt)
ORDER BY dt DESC

doesn't actually select a column dt, so you get an exception when you ask for it

temperature.setDt(resultSet.getDate("dt"));

Your other code snippets don't ever ask for a column by the name of dt.

If you want the column dt you need to SELECT it.

SELECT notes, dt, avg(temperature) temperature, ...