java - IncorrectResultSetColumnCountException : Incorrect column count: expected 1, 实际 38

Question

我正在使用 JdbcTemplate 从数据库中检索 Bean。这是我的方法:

public List<trackerv3Livedata>  getTrackerData() {
    return List<trackerv3Livedata> live = (List<trackerv3Livedata>) jdbcTemplate.queryForList("select * from mmitrackerv3_livedata where accountid =?",new Object[]{aid}, trackerv3Livedata.class);
}

而trackerv3Livedata bean结构如下:

public class trackerv3Livedata implements Serializable {

    private static final long serialVersionUID = 2409168269491619888L;

    private int deviceid;
    private Long timestamp;
    private Mmitrackerv3Device mmitrackerv3Device;
    private Mmitrackerv3Account mmitrackerv3Account;
    private double latitude;
    private double longitude;
    private Double altitude;
    private Double speedkph;
    private Double heading;
    private Double gpssignal;
    private Integer geozoneid;
    private Double distancekm;
    private Double gsmsignal;
    private Double mainpower;
    private Integer laststatustime;
    private Double internalbattry;
    private Double temperature;
    private Short dinput1;
    private Short dinput2;
    private Short dinput3;
    private Short dinput4;
    private Short dinput5;
    private Short dinput6;
    private Short dinput7;
    private Short dinput8;
    private Short ainput1;
    private Short ainput2;
    private Short ainput3;
    private Short ainput4;
    private Short doutput1;
    private Short doutput2;
    private Short doutput3;
    private Short doutput4;

    /* There are Some Getter And Setter Method With Constructor */
}

在我的情况下，我的查询完全有可能不会被点击，所以我的问题是如何绕过以下错误消息。

org.springframework.jdbc.IncorrectResultSetColumnCountException: Incorrect column count: expected 1, actual 38

在我看来，我应该只返回一个 null 而不是抛出异常。我怎样才能解决这个问题？提前致谢。

Answer 1

JdbcTemplate 方法

queryForList(String sql, Class<T> elementType)

对于单列查询很有用，您只能指定列类型。如果ResultSet中需要多列，使用更准确

query(String sql, RowMapper<T> rowMapper)

作为 RowMapper 的实现，您可以使用自己的，或者

jdbcTemplate.query(sql, new BeanPropertyRowMapper<T>(clazz));

所以你的情况可能是:

public List<Trackerv3Livedata> getTrackerData() {
    String sql = "SELECT * FROM mmitrackerv3_livedata mlive " +
                 "JOIN mmitrackerv3_device mdevice ON mlive.accountid = " +
                 "mdevice.accountid WHERE mlive.accountid = " + aid;

    return jdbcTemplate.query(sql,
        new BeanPropertyRowMapper<Trackerv3Livedata>(Trackerv3Livedata.class));
}