JPA枚举比较不相等失败

Question

我使用的是JPA 2.1.2。

我想执行一个带有where子句的select查询。where语句应该比较(不等于)存储在数据库(字符串)中的枚举。

@Entity
@Table(name = "MY_ENTITY")
public class MyEntity implements Serializable {

    @Column(name = "REMINDER_STATE")
    @Enumerated(EnumType.STRING)
    private ReminderStage reminderStage;

    ...
}

class DaoImpl{
 ....

    @Override
    public List<MyEntity> findAll(ReminderStage stage) {
        return em.createQuery("SELECT c FROM MyEntity c  WHERE  c.reminderStage != :reminderStage", MyEntity.class)
                .setParameter("reminderStage", stage).getResultList();

    }
}

但是当我执行查询时，我得到了以下异常：

...
[28.07.14 08:27:07:910 CEST] 0000004e SystemErr     R Caused by: <openjpa-2.1.2-SNAPSHOT-r422266:1530146 nonfatal user error> org.apache.openjpa.persistence.ArgumentException: An error occurred while parsing the query filter 'SELECT c FROM CertInfo c  WHERE  c.reminderStage != :reminderStage'. Error message: org.apache.openjpa.kernel.jpql.TokenMgrError: Lexical error at line 1, column 50.  Encountered: "!" (33), after : ""
[28.07.14 08:27:07:910 CEST] 0000004e SystemErr     R   at org.apache.openjpa.kernel.jpql.JPQLExpressionBuilder$ParsedJPQL.parse(JPQLExpressionBuilder.java:2449)
[28.07.14 08:27:07:910 CEST] 0000004e SystemErr     R   at org.apache.openjpa.kernel.jpql.JPQLExpressionBuilder$ParsedJPQL.<init>(JPQLExpressionBuilder.java:2432)
[28.07.14 08:27:07:910 CEST] 0000004e SystemErr     R   at org.apache.openjpa.kernel.jpql.JPQLParser.parse(JPQLParser.java:49)
[28.07.14 08:27:07:910 CEST] 0000004e SystemErr     R   at org.apache.openjpa.kernel.ExpressionStoreQuery.newCompilation(ExpressionStoreQuery.java:154)
[28.07.14 08:27:07:910 CEST] 0000004e SystemErr     R   at org.apache.openjpa.kernel.QueryImpl.newCompilation(QueryImpl.java:672)
[28.07.14 08:27:07:911 CEST] 0000004e SystemErr     R   at org.apache.openjpa.kernel.QueryImpl.compilationFromCache(QueryImpl.java:654)
[28.07.14 08:27:07:911 CEST] 0000004e SystemErr     R   at org.apache.openjpa.kernel.QueryImpl.compileForCompilation(QueryImpl.java:620)
[28.07.14 08:27:07:911 CEST] 0000004e SystemErr     R   at org.apache.openjpa.kernel.QueryImpl.compileForExecutor(QueryImpl.java:682)
[28.07.14 08:27:07:911 CEST] 0000004e SystemErr     R   at org.apache.openjpa.kernel.QueryImpl.compile(QueryImpl.java:589)
[28.07.14 08:27:07:911 CEST] 0000004e SystemErr     R   at org.apache.openjpa.persistence.EntityManagerImpl.createQuery(EntityManagerImpl.java:996)
[28.07.14 08:27:07:911 CEST] 0000004e SystemErr     R   at com.ibm.ws.persistence.EntityManagerImpl.createQuery(EntityManagerImpl.java:107)
[28.07.14 08:27:07:911 CEST] 0000004e SystemErr     R   at com.ibm.ws.persistence.EntityManagerImpl.createQuery(EntityManagerImpl.java:86)
[28.07.14 08:27:07:911 CEST] 0000004e SystemErr     R   at com.ibm.ws.persistence.EntityManagerImpl.createQuery(EntityManagerImpl.java:34)
[28.07.14 08:27:07:911 CEST] 0000004e SystemErr     R   at org.apache.openjpa.persistence.EntityManagerImpl.createQuery(EntityManagerImpl.java:974)
[28.07.14 08:27:07:911 CEST] 0000004e SystemErr     R   at com.ibm.ws.jpa.management.JPATxEmInvocation.createQuery(JPATxEmInvocation.java:353)
[28.07.14 08:27:07:911 CEST] 0000004e SystemErr     R   at com.ibm.ws.jpa.management.JPAEntityManager.createQuery(JPAEntityManager.java:550)
[28.07.14 08:27:07:911 CEST] 0000004e SystemErr     R   at ...findAll(DaoImpl.java:271)
[28.07.14 08:27:07:911 CEST] 0000004e SystemErr     R   ... 13 more

当我从不等于(!=)更改为等于(=)时，查询可以正常工作。

那么我如何使用枚举比较和不相等呢？

Answer 1

不等于？<>使用此运算符。

JPQL operators (根据第10.2.5.6节。JPQL Language Reference)

1. 导航运算符(.)
2. 算术运算符：+、-一元*、/乘法和除法+、-加法和subtraction
3. Comparison运算符：=、>、>=、<、<=、<> (不相等)、NOT MEMBER、NOT LIKE、NOT IN、IS NOT NULL、IS NOT EMPTY、NOT MEMBER OF
4. 逻辑运算符: NOT

OR

Answer 2

使用Jpql时，"not equal"的正确运算符是<>。所以，像这样更新你的代码：

 return em.createQuery("SELECT c FROM MyEntity c  WHERE  c.reminderStage <> :reminderStage", MyEntity.class)
                .setParameter("reminderStage", stage).getResultList();

Remove !=改用<>。