C#外部应用于LINQ

Question

如何在LINQ中实现外部应用？我有一点问题.

这是我正在使用的SQL查询.

SELECT u.masterID
      ,u.user
      ,h.created
FROM dbo.Users u
OUTER APPLY (SELECT TOP 1 * FROM UserHistory h where h.masterID = u.masterID ORDER BY created DESC) h

Answer 1

from u in Users 
join UserHistory on u.masterID equals h.masterID into h 
select new {
  u.masterID,
  u.user,
  Created = h.Select(x => x.created).OrderByDescending(c => c).FirstOrDefault()
}

或者,与协会:

from u in Users
let created = u.UserHistories.Select(x => x.created).OrderByDescending(c => c).FirstOrDefault()
select new
{
  u.masterID,
  u.user,
  Created = created
}

Answer 2

from u in Users
join UserHistory on u.masterID equals h.masterID into h
select new {u.masterID, u.user, h.created.OrderByDescending().First()}