java – JPA：查询根据实体类中定义的外键值获取结果？

发布时间：2020-12-15 00:00:23 所属栏目：Java 来源：网络整理

导读：Netbean 6.9从此SQL Server 2008表生成以下JPA实体类：我想获得具有特定SKU值的所有ProductDescriptors.像这样的东西： SELECT * FROM ProductDescriptors WHERE SKU='something' 给定实体类,获得结果的Java代码是什么？谢谢. @Entity@Table(name = "Produ

Netbean 6.9从此SQL Server 2008表生成以下JPA实体类：

我想获得具有特定SKU值的所有ProductDescriptors.像这样的东西：

SELECT * FROM ProductDescriptors WHERE SKU='something'

给定实体类,获得结果的Java代码是什么？

谢谢.

@Entity
@Table(name = "ProductDescriptors")
@NamedQueries({
    @NamedQuery(name = "ProductDescriptors.findAll",query = "SELECT p FROM ProductDescriptors p"),@NamedQuery(name = "ProductDescriptors.findByDescriptorID",query = "SELECT p FROM ProductDescriptors p WHERE p.descriptorID = :descriptorID"),@NamedQuery(name = "ProductDescriptors.findByLanguageCode",query = "SELECT p FROM ProductDescriptors p WHERE p.languageCode = :languageCode"),@NamedQuery(name = "ProductDescriptors.findByTitle",query = "SELECT p FROM ProductDescriptors p WHERE p.title = :title"),@NamedQuery(name = "ProductDescriptors.findByIsDefault",query = "SELECT p FROM ProductDescriptors p WHERE p.isDefault = :isDefault"),@NamedQuery(name = "ProductDescriptors.findByBody",query = "SELECT p FROM ProductDescriptors p WHERE p.body = :body")})
public class ProductDescriptors implements Serializable {
    private static final long serialVersionUID = 1L;
    @Id
    @Basic(optional = false)
    @Column(name = "DescriptorID")
    private Integer descriptorID;
    @Basic(optional = false)
    @Column(name = "LanguageCode")
    private String languageCode;
    @Basic(optional = false)
    @Column(name = "Title")
    private String title;
    @Basic(optional = false)
    @Column(name = "IsDefault")
    private boolean isDefault;
    @Basic(optional = false)
    @Column(name = "Body")
    private String body;
    @JoinColumn(name = "SKU",referencedColumnName = "SKU")
    @ManyToOne(optional = false)
    private Products products;

…

解决方法

像这样的东西：

@PersistenceContext( unitName = "youPersistenceUnitHere" )
private EntityManager _entityManager;

public List<ProductDescriptors> getProductDescriptorsBySku( String sku ) {
   Query query = _entityManager.createQuery( "Select ProductDescriptors from ProductDescriptors pd where pd.products.sku = ?1" );
   query.setParameter( 1,sku );
   return new ArrayList<ProductDescriptors>( query.getResultList() );
}

（编辑：李大同）

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