Java JPA：查询以根据实体类中定义的外键值获取结果？
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JPA: query to get results based on value of foreign key defined in the entity class?
提问by Sajee
Netbean 6.9 generated the following JPA entity class from this SQL Server 2008 table:
Netbean 6.9 从此 SQL Server 2008 表生成了以下 JPA 实体类：
I want to get all the ProductDescriptors that have a specific SKU value. Something like this:
我想获取所有具有特定 SKU 值的 ProductDescriptor。像这样的东西：
SELECT * FROM ProductDescriptors WHERE SKU='something'
Given the entity class, what's the Java code to get the results?
给定实体类，获取结果的 Java 代码是什么？
Thanks.
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;
...
...
采纳答案by javamonkey79
Something like this:
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() );
}
