Question

我正在使用JPA 2.1.2。

我想用where子句执行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（！=）变为等于（=）时，查询工作正常。

那么如何使用不相等的枚举比较？

Answer 1

不相等？ <>使用此运算符。

JPQL运算符（根据章节10.2.5.6。 JPQL Language Reference）

导航操作员（。）
算术运算符：+， - 一元*，/乘法和除法+， - 加法和减法
比较运算符：=，＆gt;，＆gt; =，＆lt;，＆lt; =，＆lt;＆gt; （不等于），[NOT] BETWEEN，[NOT] LIKE，[NOT] IN，IS [NOT] NULL，IS [NOT] EMPTY，[NOT] MEMBER [OF]
逻辑运算符：NOT AND OR

Answer 2

使用Jpql时，＆＃34;不等于＆＃34; 的正确运算符为＆lt;＆gt; 。所以，像这样更新您的代码：

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

删除！= 使用＆lt;＆gt; 。

JPA枚举比较不等于失败

2 个答案: