Java JPA NamedQuery与聚合函数和分组依据一起使用
我的数据库表Foo上有几条记录,我需要聚合一列来求和它的值 表示该表的实体如下所示:Java JPA NamedQuery与聚合函数和分组依据一起使用,java,jpa,named-query,Java,Jpa,Named Query,我的数据库表Foo上有几条记录,我需要聚合一列来求和它的值 表示该表的实体如下所示: @Entity @Table(name = "FOO") @NamedQueries({ @NamedQuery(name = "Foo.total", query = "SELECT f.id, sum(f.someInt) AS SOME_INT, f.parentId FROM Foo f where f.parentId = 'root' group by p.parentId"), @NamedQ
@Entity
@Table(name = "FOO")
@NamedQueries({
@NamedQuery(name = "Foo.total", query = "SELECT f.id, sum(f.someInt) AS
SOME_INT, f.parentId FROM Foo f where f.parentId = 'root' group by
p.parentId"),
@NamedQuery(name = "Foo.findAll", query = "SELECT f from Foo f") })
public class Foo {
@Id
@Column(name = "ID", insertable = false, updatable = false)
private String id;
@Column(name = "PARENT_ID", insertable = false, updatable = false)
private String parentId;
@Column(name = "SOME_INT", insertable = false, updatable = false)
private Integer someInt;
public Foo() {
}
}
如果我在我的dao服务bean上调用这个:
entityManager.createNamedQuery("Foo.total", Foo.class).getResultList();
我得到这个错误:
Caused by: java.lang.IllegalArgumentException: Cannot create TypedQuery for query with more than one return using requested result type [Foo]
JPA似乎无法匹配对象Foo的返回值。如果是这样的话,我怎样才能让它工作呢
如果我将另一个@NamedQuery称为“Foo.findAll”,它可以正常工作
SELECT f.id, sum(f.someInt) AS SOME_INT, f.parentId FROM Foo f
where f.parentId = 'root' group by p.parentId"
此查询不返回Foo实体,而是返回投影
您可能希望创建一个具有所选属性的自定义POJO,并在创建查询时将其用作返回类型
见和