[英]Java Persistence Query Language JOIN
我有两个表:
A(bigint id, ...)
B(bigint id, varchar name, bigint id_A)
现在我想从B中存在的A中获取所有行(并且B中的那些行具有名称,例如Andy)
请帮助我创建动态查询
A级
@Entity
@Table(name = "A", schema = "mySchema")
@Cache(usage = CacheConcurrencyStrategy.TRANSACTIONAL)
public class A{
@Id
private Long id;
}
B级
@Entity
@Table(name = "B",
schema = "mySchema",
uniqueConstraints = { @UniqueConstraint(columnNames = {
"some_id", "id_A" }) })
public class B{
@Id
@GeneratedValue(strategy = GenerationType.AUTO, generator = "Seq")
@SequenceGenerator(name = "Seq", sequenceName = "mySchema.mySeq")
private Long id;
@OneToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "id_A", nullable = false)
private A a;
@Column(name = "id_A", updatable = false, insertable = false)
private Long IdA;
}
有几个奇怪的部分。 例如:
@OneToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "id_A", nullable = false)
private A a;
@Column(name = "id_A", updatable = false, insertable = false)
private Long IdA;
使用@JoinColumn
批注,您告诉JPA提供程序它应该使用指定的列进行内部映射,但是使用IdA字段,您试图自己管理该列。 会是什么?
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