如何查询和选择嵌入式id列

Question

我在java中有两个类，分别是txn和txnID，我想从嵌入表中检索txnID值，下面是我的txn类结构：

public class TbTxn implements Serializable{

@EmbeddedId
private TbTxnId id;

private Long   acctid;
private String hmbrchcd;
private String crdno;
//all the getter and setter code
}

以下是嵌入式类结构：

@Embeddable
public class TbTxnId implements Serializable{

private Date txndttm;
private Long txnid;

@Column(name="TXNDTTM")
public Date getTxndttm() {
    return txndttm;
}
 public void setTxndttm(Date txndttm) {
    this.txndttm = txndttm;
}

 @Column(name="TXNID")
public Long getTxnid() {
    return txnid;
}
public void setTxnid(Long txnid) {
    this.txnid = txnid;
}
}

我的查询语句如下：

String stmt = "select txn.id.TXNID from TbTxn txn where txn.id.TXNDTTM >= SYSDATE ";

Long count = (Long) getSession().createQuery(stmt).uniqueResult();

错误消息如下：

SEVERE: Servlet.service() for servlet [] in context with path [] threw exception [Request processing failed; nested exception is 
org.hibernate.QueryException: could not resolve property: id.TXNID of: com.domain.TbTxn [select txn.id.TXNID from com.domain.TbTxn txn where txn.id.TXNDTTM >= SYSDATE ]] with root cause
org.hibernate.QueryException: could not resolve property: id.TXNID of: com.domain.TbTxn [select txn.id.TXNID from com.domain.TbTxn txn where txn.id.TXNDTTM >= SYSDATE ]

Answer 1

String stmt = "select txn.id.txnid from TbTxn txn where txn.id.txndttm >= SYSDATE ";

我们应该注意实体类名及其属性的情况。