nhibernate/hibernate、查找表和对象设计

我有两张桌子。列为customerid、invoicedate、value、invoicetypeid(customerid和invoicedate组成组合键)的发票,列为invoicetypeid和invoicetypename的发票。

我知道我可以创建我的对象,比如:

public class Invoice
{
    public virtual int CustomerID { get; set; }
    public virtual DateTime InvoiceDate { get; set; }
    public virtual decimal Value { get; set; }
    public virtual InvoiceType InvoiceType { get; set; }
}

public class InvoiceType
{
    public virtual InvoiceTypeID { get; set; }
    public virtual InvoiceTypeName { get; set; }
}

因此生成的sql看起来像:

SELECT CustomerID, InvoiceDate, Value, InvoiceTypeID FROM Invoice WHERE CustomerID = x AND InvoiceDate = y
SELECT InvoiceTypeID, InvoiceTypeName FROM InvoiceType WHERE InvoiceTypeID = z

但是,如果执行两个select查询来检索数据,我宁愿使用一个查询。我还想避免使用子对象进行简单的查找列表。所以我的东西看起来像:

public class Invoice
{
    public virtual int CustomerID { get; set; }
    public virtual DateTime InvoiceDate { get; set; }
    public virtual decimal Value { get; set; }
    public virtual InvoiceTypeID { get; set; }
    public virtual InvoiceTypeName { get; set; }
}

我的sql看起来像:

SELECT CustomerID, InvoiceDate, Value, InvoiceTypeID 
FROM Invoice INNER JOIN InvoiceType ON Invoice.InvoiceTypeID = InvoiceType.InvoiceTypeID
WHERE CustomerID = x AND InvoiceDate = y

我的问题是如何创建这个映射?

我尝试过使用join,但这尝试过使用customerid和invoicedate进行连接,我是否遗漏了一些明显的东西?

谢谢