Question

我有两个实体类FlcDrawingRequests和FlcDrawingRequestStats。从两个表中获取数据，我尝试使用下面的query从两个表中获取数据。无法获取数据。能否请任何一个人帮我这个忙。

 private static final String querystat = "select dr, ds from 
 FlcDrawingRequests AS dr,FlcDrawingRequestStats AS ds where dr.id=ds.request_id";

下面是两个实体类

FlcDrawingRequests

@Entity(name = "FlcDrawingRequests")
@Table(name = "drawing_requests", catalog = FlcWsDao.DB_SCHEMA_NAME)
public class FlcDrawingRequests {

    @Id
    private String id;
    @Column(name = "creation_time", nullable = false, updatable = false)
    private Date creation_time;
    @Column(name = "drawing_spec_format", length = 16)
    private String drawing_spec_format;
    @Column(name = "end_time")
    private Date end_time;
}

FlcDrawingRequests

@Entity(name = "FlcDrawingRequestStats")
@Table(name = "drawing_request_stats", catalog = FlcWsDao.DB_SCHEMA_NAME)
public class FlcDrawingRequestStats {
    @Id
    private String request_id;
    @Column(name = "bb", length = 11)
    private Integer bb;
    @Column(name = "car_offset_g", length = 11)
    private Integer car_offset_g;
    @Column(name = "car_sling_type", length = 32)
    private String car_sling_type;
    @Column(name = "car_type", length = 16)
    private String car_type;
    @Column(name = "ch", length = 11)
    private Integer ch;
}

下面是查询执行：

StringBuilder queryBuilder = new StringBuilder(querystat);
System.out.println("startDate--->" + startDate);
Query query =getEntityManager().createQuery(queryBuilder.toString());
System.out.println("query.list();--->" + query.getResultList().size());
return query.getResultList();

Answer 1

 private static final String querystat = "SELECT dr, ds FROM 
 FlcDrawingRequests dr,FlcDrawingRequestStats ds WHERE dr.id LIKE ds.request_id";

并且结果必须存储在List<Object[2]>中，因此您必须具有：

List<Object[2]> result=query.getResultList();

因此，这里有一个表的列表，该表的大小等于2，列表中的每个元素都包含两个Object，第一个是FlcDrawingRequests，第二个是FlcDrawingRequestStats。

合并两个实体并获取数据

1 个答案: