C# nhibernate fluent-nhibernate queryover

有关 QueryOver 和WhereExists 的帮助

发布于 2024-10-20 11:17:38 字数 584 浏览 3 评论 0原文

我有一个问题。我有人和猫。每个人都有一些猫（猫中有一个外键指向人中的主键）。每只猫都有一个年龄。我想选择拥有“老”猫的人。我想要这些人的所有猫，而不仅仅是“老”猫。我需要使用 QueryOver 语法来完成此操作。

在 T-SQL 中，它会是这样的：

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)

我知道我必须使用子查询，并且我可以轻松地使用“旧”nhibernate 语法（Criteria/DetachedCriteria），但我不能用 QueryOver 语法来做到这一点。

我不想要“IN”状态。我的主键是一个复杂的键，所以我无法使用 IN 来完成它。

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

原文

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( ??? );

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夏九 2024-10-27 11:17:38

示例取自此页面并进行改编（用我自己的类进行测试）：

这个技巧似乎是使用别名。

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>();

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>();

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