Question

鉴于以下领域模式:

Dog { Id, Name, Color }

Color { Id, Name }

How do I get the Colors for which there are dogs with NHibernate.Linq. In SQL I would

SELECT Color.Id, Color.Name FROM Color 
    WHERE Id IN 
    (SELECT DISTINCT Dog.ColorId FROM Dog);

Answer 1

这一工作可以:

Colors.Where(c => Dogs.Any(d => d.Color.Equals(c)))

然而,如果你完全按照肤色识别符号进行对比,则试图这样做:

Colors.Where(c => Dogs.Any(d => d.Color.Id == c.Id))

These will give you all of the colors which are used by the dogs.

Answer 2

如果你有一份价值清单,那么国家自由委员会目前只能从林克的询问中作出陈述(3.2.0.GA)。它永远不会产生一份仅未执行的声明。

页: 1

Answer 3

You can make a join :

from c in Color 
from d in dog
WHERE d.ColorId == c.Id 
select c

But that s still a join, so you could as easily try to get the dog colors with one query:

var dogColors = (from d in Dogs
                 select d.ColorId).Distinct().List()

接着,科罗人:

from c in Color
where dogColors.Contains(c.Id)
select c

Answer 4

为什么你们需要一个排位?

这是公正的。

from d in db.Dogs 
select d.Color