Linq查询子查询

Question

我有一个名为UserPaymentHistory的实体,包含Id,UserId,Price,PaymentDate.我需要获得具有最后PaymentDate的User的那一行.

我可以这样查询:

var lastPaymentDate =
    db.Repository<UserPayment>()
            .Where(u => u.UserId == 1)
            .Select(x => x.PaymentDate)
            .Max();

然后:

var userPayment = db.Repository<UserPayment>()
                      .Where(u => u.UserId == request.UserId 
                      && u.PaymentDate == lastPaymentDate).Single();

有什么办法可以在一个查询中获得该记录吗？:)

Answer 1

PaymentDate按降序付款并选择第一个:

var userPayment = db.Repository<UserPayment>()
                      .Where(u => u.UserId == request.UserId)
                      .OrderByDescending(u => u.PaymentDate)
                      .FirstOrDefault();