我有一份人们的身份证和名字的名单，还有一份人们的身份证和姓氏的名单。有些人没有名字，有些人没有姓;我想在这两个列表上做一个完整的外部连接。
下面列出:
ID FirstName
-- ---------
1 John
2 Sue
ID LastName
-- --------
1 Doe
3 Smith
应该生产:
ID FirstName LastName
-- --------- --------
1 John Doe
2 Sue
3 Smith
我已经发现了相当多的解决方案的“LINQ外部连接”，它们看起来都很相似，但似乎真的是离开外部连接。
到目前为止我的尝试是这样的:
private void OuterJoinTest()
{
List<FirstName> firstNames = new List<FirstName>();
firstNames.Add(new FirstName { ID = 1, Name = "John" });
firstNames.Add(new FirstName { ID = 2, Name = "Sue" });
List<LastName> lastNames = new List<LastName>();
lastNames.Add(new LastName { ID = 1, Name = "Doe" });
lastNames.Add(new LastName { ID = 3, Name = "Smith" });
var outerJoin = from first in firstNames
join last in lastNames
on first.ID equals last.ID
into temp
from last in temp.DefaultIfEmpty()
select new
{
id = first != null ? first.ID : last.ID,
firstname = first != null ? first.Name : string.Empty,
surname = last != null ? last.Name : string.Empty
};
}
}
public class FirstName
{
public int ID;
public string Name;
}
public class LastName
{
public int ID;
public string Name;
}
但结果是:
ID FirstName LastName
-- --------- --------
1 John Doe
2 Sue
我做错了什么?
