我是 JPA 的新手...我从这个 JPQL 查询中得到一个空值。我正在尝试获取所有 ExamName 列数据,但它返回一个空值..
ExamRepository 接口:
@Repository
public interface ExamRepository extends JpaRepository<ExamEntity,Integer>
{
@Query("SELECT e.ExamName from ExamEntity e")
public List<ExamEntity> getExams();
}
ExamEntity class:
@Entity
@Table(name="exams")
public class ExamEntity {
@Id
@GeneratedValue
@Column(length =100)
private int id;
@Column(nullable=false,length =100)
private String ExamName;
@Column(nullable=false,length =100)
private String ExamDate;
}
答案 0 :(得分:0)
您的选择和返回值有问题。如果您选择考试名称或选择实体,您需要返回一个字符串列表。
@Query("SELECT e.ExamName from ExamEntity e")
public List<String> getExams();
或
// This is redundant however as JpaRepository has findAll()
@Query("SELECT e from ExamEntity e")
public List<ExamEntity> getExams();