linq-to-entities - LINQ to Entities, how to return all records from the Parent table?

Question

I am unable to select all the records from the parent table using Linq to Entities.

This is a simple DB design (image below):

Image Link (Dead Link)

This is the exact output I want using Linq to Entities or Linq to SQL (image below):

Image Link (Dead Link)

When I use Linq to Entities or Linq To Sql, I can only get the records from the child table that has a foreign key relation. I am not able to get the null values as shown above.

I want to have the null values show just like when you use left outer join.

Thanks for any help.

Answer 1

from entity in MyContext.EntityType.Include("ChildEntitiesNavigationPropertyName")
select entity;

这将返回 EntityType 的所有实例，以及 ChildEntitiesNavigationPropertyName（如果存在）。对于表格形式，使用匿名类型：

from entity in MyContext.EntityType.Include("ChildEntitiesNavigationPropertyName")
select new {ParentProperty = entity.ParentProperty, 
            ChildProperty  = entity.ChildEntitiesNavigationPropertyName.ChildProperty};

对于 1..* 属性：

from entity in MyContext.EntityType.Include("ChildEntitiesNavigationPropertyName")
from child in entity.ChildEntitiesNavigationPropertyName.DefaultIfEmpty()
select new {ParentProperty = entity.ParentProperty, 
            ChildProperty  = child.ChildProperty};

Answer 2

我很确定您可以从员工中进行选择，然后在 LINQ 中进行左连接，就像这样（我在这台机器上没有 VS）：

var results = from e in dbContext.Employees join s in dbContext.Sales on e.EmployeeID equals s.EmployeeID select new { e, s };

您可能想要选择您想要的列。希望它能给你你想要的结果。