Orm 如何在jpql查询中只查询超类实体?
我拥有以下实体:Orm 如何在jpql查询中只查询超类实体?,orm,jpa,eclipselink,jpa-2.0,jpql,Orm,Jpa,Eclipselink,Jpa 2.0,Jpql,我拥有以下实体: @Entity @Inheritance(strategy=InheritanceType.SINGLE_TABLE) @DiscriminatorColumn(name="orderType", discriminatorType=DiscriminatorType.STRING) @DiscriminatorValue(value="BASE") @Table(name = "orders") public class OrderEntity implements Seri
@Entity
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name="orderType", discriminatorType=DiscriminatorType.STRING)
@DiscriminatorValue(value="BASE")
@Table(name = "orders")
public class OrderEntity implements Serializable {
...
及
我可以找到具有以下jpql的所有子类(RecurringOrderEntity):
Query q = em.createQuery(
"SELECT o from RecurringOrderEntity o where "
+ "o.cancellationDate is null "
+ "and o.maxOccurrences = o.occurrence");
JPQL语法是什么,用于只查找不是RecurringOrderEntity实例的实体
我使用Eclipselink 2.0.0作为JPA提供商
谢谢
JPQL语法是什么,用于只查找不是RecurringOrderEntity实例的实体
使用带有type
运算符的实体类型表达式。类似这样的情况(不确定您想要的确切查询,但您已经知道了):
实体类型文字是
由实体名称指定
使用实体的Java类
作为输入参数来指定
实体类型
示例:
SELECT e
FROM Employee e
WHERE TYPE(e) IN (Exempt, Contractor)
SELECT e
FROM Employee e
WHERE TYPE(e) IN (:empType1, :empType2)
SELECT e
FROM Employee e
WHERE TYPE(e) IN :empTypes
SELECT TYPE(e)
FROM Employee e
WHERE TYPE(e) <> Exempt
选择e
来自雇员e
其中(e)类为(豁免,承包商)
选择e
来自雇员e
其中(:empType1,:empType2)中的类型(e)
选择e
来自雇员e
其中类型(e)位于:空类型
选择类型(e)
来自雇员e
其中(e)类豁免
在不知道任何子类的情况下,有没有办法做到这一点?
SELECT o
FROM OrderEntity o
WHERE TYPE(o) <> RecurringOrderEntity
AND o.cancellationDate is null
AND o.maxOccurrences = o.occurrence
entity_type_expression ::=
type_discriminator |
entity_type_literal |
input_parameter
type_discriminator ::=
TYPE(identification_variable |
single_valued_object_path_expression |
input_parameter )
SELECT e
FROM Employee e
WHERE TYPE(e) IN (Exempt, Contractor)
SELECT e
FROM Employee e
WHERE TYPE(e) IN (:empType1, :empType2)
SELECT e
FROM Employee e
WHERE TYPE(e) IN :empTypes
SELECT TYPE(e)
FROM Employee e
WHERE TYPE(e) <> Exempt