帮助QueryOver和WhereExists [英] Help with QueryOver and WhereExists

问题描述

我有一个问题。我有人员和猫。每个人都有一些猫（有猫的外键指向人的主键）。每只猫都有一个时代。我要选择有老猫的个人。我想这些人的所有的猫，而不是只有老猫。
我需要与QueryOver语法来做到这一点。

在T-SQL它会是这样的：

  SELECT * P.，C * 
从人p 
 LEFT JOIN猫C 
关于P.Id = C.OwnerId 
在存在（
选择1 
 FROM猫C2 
其中P.Id = C2.OwnerId和C2.Age→5）
  

我知道我必须使用子查询，我可以很容易地与旧的NHibernate语法（条条/的DetachedCriteria），但我不能做到在QueryOver语法。

我不希望入状态。我的主键是一个复杂的关键，所以我不能用IN做到这一点。

 变种人= session.QueryOver<人> .WithSubquery.WhereExists（???）; 
  

解决方案

从的this页面和调整（用我自己的类测试）：

诀窍似乎在用。别名

 人员personAlias = NULL; 
 
&IList的LT;人>者= 
 session.QueryOver&所述;人>（（）=> personAlias）.WithSubquery 
 .WhereExists（QueryOver.Of&所述;目录>（）
。凡（C =&℃。年龄大于5）
。而（C => c.Owner.Id == personAlias.Id）
。选择（C => c.Owner））
&的.List LT;人>（）; 
  

I have a problem. I have Persons and Cats. Each Person has some Cats (there is a foreign key in Cats that points to the primary key in Persons). Each Cat has an Age. I want to select the Persons that have "Old" Cats. I want ALL the Cats of these persons, and not only the "Old" Cats. I need to do it with the QueryOver syntax.

In T-SQL it would be something like:

SELECT P.*, C.*
FROM Persons P
LEFT JOIN Cats C
    ON P.Id = C.OwnerId
WHERE EXISTS (
    SELECT 1
    FROM Cats C2
    WHERE P.Id = C2.OwnerId AND C2.Age > 5)

I know I have to use the subqueries, and I could to easily with the "old" nhibernate syntax (the Criteria/DetachedCriteria), but I can't do it in QueryOver syntax.

I DON'T want an "IN" condition. My Primary Key is a complex key, so I can't do it with the IN.

var persons = session.QueryOver<Person>.WithSubquery.WhereExists( ??? );

解决方案

Example taken from this page and adapted (tested with my own classes):

The trick seems to be using an alias.

Person personAlias = null;

IList<Person> persons = 
        session.QueryOver<Person>(() => personAlias).WithSubquery
          .WhereExists(QueryOver.Of<Cat>()
             .Where(c => c.Age > 5)
             .And(c => c.Owner.Id == personAlias.Id)
             .Select(c => c.Owner))
          .List<Person>();

这篇关于帮助QueryOver和WhereExists的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！