如何使用Nhibernate QueryOver联接两个非冲突定义列的两个表 [英] How to join Two tables of two non relashinship defined columns using Nhibernate QueryOver

问题描述

我要使用NHibernate QueryOver，使用两个未在映射中定义为关系的列来联接两个表.

Using NHibernate QueryOver, I want to join two tables using two columns which are not defined in the mapping as a relationship.

例如这不是我的确切情况，但这可以解释

E.g. This is not my exact scenario but this can explain that

表格:

Employee(Id, Name, DepartmentId, SomeCode,Address)

Department (Id, Name, ,Code)

选择

SELECT * 
  FROM EMPLOYEE E 
  JOIN DEPARTMENT D 
    ON D.Code = E.SomeCode

有人可以告诉我如何使用NHibernate QueryOver进行此查询.请注意，未将Employee中的"SomeCode"和Department中的"Code"定义为关系. DepartmentId是外键，我可以使用JoinAlias来加入它们，但我希望以某种不同的方式来使用它.

Can someone please tell me how to do this query using NHibernate QueryOver. Note that "SomeCode" in Employee and "Code" in Department are not defined as a relationship. DepartmentId is the foreign key and I can join these using JoinAlias but I want it in a somewhat different way.

推荐答案

还有类似的问题，例如

• NHibernate(+ FluentNhibernate):连接两个分离的表
• 没有表的映射关联的休眠标准投影

• NHibernate (+ FluentNhibernate) : Join two detached tables
• Hibernate Criteria Projection without mapped association of tables

答案是:

1. 使用 HQL 和CROSS JOIN(与WHERE一起使用)
2. > Criteria的方法否

1. either use HQL and CROSS JOIN (with WHERE)
2. There is NO way how to do that with QueryOver/Criteria)

查看文档:

可能会出现多个类，从而导致笛卡尔积或交叉"联接.

Multiple classes may appear, resulting in a cartesian product or "cross" join.

from Formula, Parameter

from Formula as form, Parameter as param

因此，在您的情况下使用HQL，我们可以这样做:

So using HQL in your case, we can do it like this:

SELECT ...
FROM EMPLOYEE E, DEPARTMENT D 
WHERE D.Code = E.SomeCode
...

但是我建议:在代码中创建该映射.简单介绍many-to-one关系.它会延迟加载(仅在使用时才加载)，并且会很好地满足我们的需求-在QueryOver中用作Join

BUT I would suggest: create that mapping in the code. Simply introduce many-to-one relation. It will be loaded lazily (only if used) and will nicely serve to our needs - be used in QueryOver as a relation for Join

如果存在这种关系，并且该关系存在于业务对象域中，那么我们就不用害怕使用它.我们可以通过安全性等方式将其隐藏...

If there is such relation, if this exist in the business object domain, we should not be scared to use it. We can hide it via security etc...

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