Java 一对一关系中null列的HQL左外部联接

不管B表中是否有匹配的记录，左外部联接都应该从左表中获取所有数据，但如果左表右id列为空，则无法获取记录

我在解释更多

在数据模型Order.java中，它是我的左表，有一对一的关系

@OneToOne(targetEntity = OrderShippingDetail.class, optional=true, cascade = {CascadeType.ALL})
@JoinColumn(name = "SHIPPING_DETAIL_ID", referencedColumnName = "ID")
private OrderShippingDetail shippingDetail;

HQL是：

    hql = "SELECT " +
            "o.id as id, " +
            "o.createTime as createTime, " +
            "o.customerEmailAddress as customerEmailAddress, " +
            "o.customerPhoneNumber as customerPhoneNumber, " +
            "o.customerNote as customerNote, " +
            "o.invoicePrintedFlag as invoicePrintedFlag, " +
            "shippingAddress.address.personName as shippingPersonName, " +
            "shippingDetail.shippingCompany.id as shippingCompanyId, "+
            "shippingDetail.shippingCompany.name as shippingCompanyName, "+
            "shippingDetail.receiptNumber as shippingReceiptNumber, "+
            "shippingDetail.trackingNumber as shippingTrackingNumber, "+
            "shippingDetail.price as shippingPrice, "+
            "o.invoiceNumber as invoiceNumber " + 
        "FROM Order AS o " +
        "LEFT OUTER JOIN o.shippingAddress AS shippingAddress " +
        "LEFT OUTER JOIN o.shippingDetail AS shippingDetail ";

但是只有“SHIPPING\u DETAIL\u ID”不为空的记录。HQL有错误吗？它是通过建模SQL命令创建的，该命令在hibernate运行时自动创建

我发现了这个

HQL支持两种形式的关联联接：隐式和显式

上一节中显示的查询都使用显式形式， 也就是说，在from子句中显式使用join关键字。 这是推荐的表格

隐式表单不使用join关键字。相反 关联使用点表示法“取消引用”。隐式连接可以 出现在任何HQL子句中。隐式连接导致内部连接 在生成的SQL语句中

我删除了SELECT部分中的点符号，因此我的新HQL：

hql = "SELECT " +
                "o.id as id, " +
                "o.createTime as createTime, " +
                "o.customerEmailAddress as customerEmailAddress, " +
                "o.customerPhoneNumber as customerPhoneNumber, " +
                "o.customerNote as customerNote, " +
                "o.invoicePrintedFlag as invoicePrintedFlag, " +
                "shippingDetail, " +
                "o.invoiceNumber as invoiceNumber " + 
            "FROM Order AS o " +
            "LEFT OUTER JOIN o.shippingAddress AS shippingAddress " +
            "LEFT OUTER JOIN o.shippingDetail AS shippingDetail ";

---

所以，它可以工作，它返回Order表中的所有记录，但是，我不想选择ShippingDetail对象中的所有列和关系。如何解决此问题？

向查询中添加另一个显式左连接：

SELECT o.id as id, 
...,
shippingCompany.id as shippingCompanyId, 
shippingCompany.name as shippingCompanyName, 
...
FROM Order AS o
LEFT OUTER JOIN o.shippingAddress AS shippingAddress 
LEFT OUTER JOIN o.shippingDetail AS shippingDetail
LEFT OUTER JOIN shippingDetail.shippingCompany AS shippingCompany

---

我应该得到它<代码>shippingDetail.shippingCompany.id作为shippingCompanyId第一个点代表

左外部联接o.shippingDetail作为shippingDetail

，第二个点根据Hibernate文档导致内部联接。谢谢