SQL到JPQL - 哈希因公式

Posted 2021-03-31

我有这个SQL查询，它从点表返回位置，并以km为单位按距离排序。该查询适用于SQL，但我在将其转换为JPQL时遇到一些困难。我暂时使用静态值使其更容易阅读。

SQL - 有效

SELECT DISTINCT *,( 6371 * acos( cos( radians(60.1733) ) * cos( radians( spot.spot_latitude )) 
        * cos( radians(spot.spot_longitude) - radians(24.941)) + sin(radians(60.1733)) 
        * sin( radians(spot.spot_latitude)))) AS distance 

    FROM spot

    WHERE spot_id = spot_id 
        HAVING distance < 10    
        ORDER BY distance

JPQL - 不起作用

SELECT DISTINCT s, ( 6371 * acos( cos( radians(60.1733) ) * cos( radians( spot.spot_latitude ))
        * cos( radians(spot.spot_longitude) - radians(24.941)) + sin(radians(60.1733))
        * sin( radians(spot.spot_latitude)))) AS distance 

    FROM spot  

    WHERE s.spot_id = s.spot_id
        HAVING distance < 10
        ORDER BY s.distance

JPQL根本原因抛出两个异常：

    A MultiException has 2 exceptions.  They are:
1. org.eclipse.persistence.exceptions.PersistenceUnitLoadingException: 
Exception Description: An exception was thrown while searching for persistence archives with ClassLoader: ParallelWebappClassLoader
  context: skatebayBackend
  delegate: false
----------> Parent Classloader:
java.net.URLClassLoader@2f2c9b19

Internal Exception: javax.persistence.PersistenceException: Exception [EclipseLink-28018] (Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd): org.eclipse.persistence.exceptions.EntityManagerSetupException
Exception Description: Predeployment of PersistenceUnit [skatebay_pu] failed.
Internal Exception: Exception [EclipseLink-7158] (Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd): org.eclipse.persistence.exceptions.ValidationException
Exception Description: Error encountered when building the @NamedQuery [Spot.getSpotsInMyArea] from entity class [class org.eclipse.persistence.internal.jpa.metadata.queries.NamedQueryMetadata].
Internal Exception: java.lang.ClassCastException: org.eclipse.persistence.jpa.jpql.parser.NullExpression cannot be cast to org.eclipse.persistence.jpa.jpql.parser.IdentificationVariable
2. java.lang.IllegalStateException: Unable to perform operation: create on rest.SpotApi

答案

JPQL适用于实体，而不适用于数据库表。这里至少有两个选项：

确保将实体映射到表并使用正确的查询语法。但是，JPQL提供的可能性比SQL少。 因此，在您的情况下，创建本机查询会更容易，然后您可以使用普通的sql。

Query query = getEntityManager().createNativeQuery("select * from table...");
List<Object> string = query.getResultList();

另一答案

您在where子句中使用JPQL中的别名s，而是执行此操作。

SELECT DISTINCT s, ( 6371 * acos( cos( radians(60.1733) ) * cos( radians( spot.spot_latitude ))
        * cos( radians(spot.spot_longitude) - radians(24.941)) + sin(radians(60.1733))
        * sin( radians(spot.spot_latitude)))) AS distance 

    FROM spot AS s

    WHERE s.spot_id = s.spot_id
        HAVING distance < 10
        ORDER BY s.distance