Question

我是JPA的新手，我很难写我的查询。我需要计算和过滤不属于我的实体的列（状态标志取决于请求的日期参数）

这是我简化的测试实体：

@Entity
@Table(name = "test")
public class TestEntity implements Serializable, Identifiable<Long> {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "test_seq")
    @SequenceGenerator(name = "test_seq", sequenceName = "test_seq", allocationSize = 1)
    @Column
    private Long id;

    @Column(nullable = false)
    private String name;

    @Column(nullable = false)
    private ZonedDateTime date;
}

现在我的测试查询：

// simple query, with my computed status => WORKS
query = entityManager.createQuery("SELECT e.name, e.date, "
    + " CASE WHEN :date < e.date THEN 1 ELSE 0 END"
    + " FROM " + TestEntity.class.getName() + " e");

// simple query with ORDER clause => WORKS
query = entityManager.createQuery("SELECT e.name, e.date, "
    + " (CASE WHEN :date < e.date THEN 1 ELSE 0 END) AS status"
    + " FROM " + TestEntity.class.getName() + " e"
    + " ORDER BY status");

// add 'where' close => KO: 'user lacks privilege or object not found: STATUS in statement'  
query = entityManager.createQuery("SELECT e.name, e.date, "
    + " (CASE WHEN :date < e.date THEN 1 ELSE 0 END) AS status"
    + " FROM " + TestEntity.class.getName() + " e"
    + " WHERE status = 1");

// SubQuery in FROM clause => KO: unexpected token: ( near line 1, column 19
query = entityManager.createQuery("SELECT proj FROM "
    + "     (SELECT e.name, e.date, "
    + "     (CASE WHEN :date < e.date THEN 1 ELSE 0 END) AS status"
    + "     FROM " + TestEntity.class.getName() + " e) proj"
    + " WHERE proj.status = 1");

如果有人可以提供帮助;）感谢

更新1：

// a more representative query, where status(:time) is an heavy CASE
// statement with a:time parameter and multiplle return values
"SELECT e.name, e.date, status(:time) "
    + " FROM " + TestEntity.class.getName() + " e"
    + " WHERE (SELECT status(:time) FROM TestEntity.class) IN :filtered"
    + " AND e.name IN :filteredName"

这是我成功的最佳工作解决方案，但它需要双重状态计算。我在文档上找不到更好的东西，也没有google。

JPQL：过滤计算列

0 个答案: