java.sq.SQLException：找不到列

Question

I am receiving the following error:

HTTP Status 500 - Request processing failed; nested exception is
org.springframework.jdbc.BadSqlGrammarException: StatementCallback; bad SQL grammar 
[SELECT id, name FROM track WHERE category_id = 1 ORDER BY name]; nested exception is
java.sql.SQLException: Column 'category_id' not found.

But when I copy and paste the very select statement listed in the error into a mysql shell, I get the result, which is expected as the table track has the column category_id .

What could be a reason for this error?

Here is the table create statement for track :

CREATE TABLE track (
 id SERIAL
,name VARCHAR(50)
,category_id BIGINT UNSIGNED -- This references a serial (bigint unsigned)
,CONSTRAINT track_id_pk PRIMARY KEY (id)
,CONSTRAINT track_category_id_fk FOREIGN KEY
  (category_id) REFERENCES category (id)
);

Here are some lines from my dao class regarding the track table:

private static final class TrackMapper implements RowMapper<Track> {
    @Override
    public Track mapRow(ResultSet resultSet, int rowNum) throws SQLException {
        Track track = new Track();
        track.setId(resultSet.getInt("id"));
        track.setName(resultSet.getString("name"));
        track.setCategoryId(resultSet.getInt("category_id"));
        return track;
    }
}
public List<Track> getTracks(int categoryId) {
    String sql = "SELECT id, name FROM track WHERE category_id = " + categoryId + " ORDER BY name";
    return jdbcTemplate.query(sql, new TrackMapper());
}

Answer 1

Check your SQL statement -- you need to include the category_id in the column list:

String sql = "SELECT id, name, category_id FROM track WHERE category_id = " + categoryId + " ORDER BY name";

It is failing because you're trying to extract category_id from the ResultSet and it isn't there.