Question

我创建了一个原生查询

Query q=em.createNativeQuery("select *\n" +
    "from contaarticoli ca,articolo a\n" +
    "where ca.articolo=a.id\n" +
    "order by ca.qta desc\n" +
    "limit 1;");

在工作台中，我创建了一个视图：

create view contaarticoli(articolo,qta)as
(
 select a.idarticolo as articolo,sum(a.quantita) as qta
 from articoliordine a
 group by a.idarticolo
);

当我这样做时：

List<Object> lista=q.getResultList();
System.out.println(lista.get(0))

在输出中我有：[Ljava.lang.Object; @ 1c5b8a4

为什么？

Answer 1

因为你回来了List<Object[]>。每个数组具有相同的列数，对应于查询列。

Answer 2

使用Query结果和Object执行本机查询，直到您在createNativeQuery方法中定义resultClass属性。

 createNativeQuery

Query createNativeQuery(java.lang.String sqlString,
                        java.lang.Class resultClass)

    Create an instance of Query for executing a native SQL query.

    Parameters:
        sqlString - a native SQL query string
        resultClass - the class of the resulting instance(s)

如果您有一个与查询结果字段名称相同的实体，请添加resultClass = Class.class并自动创建对象

您是否正在使用2个表之间的连接，您可以使用@SqlResultSetMapping。

@SqlResultSetMapping(name="ScalarAndEntities",
    entities={
        @EntityResult(name="org.hibernate.test.annotations.query.Night", fields = {
            @FieldResult(name="id", column="nid"),
            @FieldResult(name="duration", column="night_duration"),
            @FieldResult(name="date", column="night_date"),
            @FieldResult(name="area", column="area_id")
        }),
        @EntityResult(name="org.hibernate.test.annotations.query.Area", fields = {
            @FieldResult(name="id", column="aid"),
            @FieldResult(name="name", column="name")
        })
    },
    columns={
        @ColumnResult(name="durationInSec")
    }
)

与

一起使用

Query q = entityManager.createNativeQuery(sqlQuery, "ScalarAndEntities");

详细了解如何从nativequeries here，

中检索实体

Jpa Native Query获得结果

2 个答案: