c# - 扩展相关子查询以在 LINQ 中包含另一个查询

Question

我正在尝试扩展相关子查询以在 LINQ 中包含另一个查询。在 SQL 中，这就是查询。

SELECT V.Car_ID
FROM VEHICLES V, AGREEMENTS A, AGREEMENTS A1
WHERE A.Car_ID = V.Car_ID
AND enDate >= A.Hire_Start_Date
AND stDate <= A.Hire_End_Date
AND A1.CAR_ID = V.CAR_ID
AND location = A1.Return_Location
AND A1.Return_date =
 (SELECT MAX(A2.Return_Date)
 FROM AGREEMENT A2
 WHERE A2.VEHICLE_ID = V.VEHICLE_ID
 AND A2.Return_Date < stDate)**

在一些帮助下，我已经查询了车辆是否有协议(protocol)，但我似乎无法扩展它以检查 AGREEMENT 返回位置是否与搜索位置匹配。到目前为止，这是我的代码。

var cars = from v in db.VEHICLEs
                   where !db.AGREEMENTs.Any(a => (a.CAR_ID == v.CAR_ID
                   && a.STATUS_OPEN == true
                   && enDate >= a.HIRE_START_DATE
                   && strtDate <= a.HIRE_END_DATE))
                   select v;

我的工作 LINQ 查询中缺少 sql 查询的以下部分。

AND A1.CAR_ID = V.CAR_ID
AND location = A1.Return_Location
AND A1.Return_date =
 (SELECT MAX(A2.Return_Date)
 FROM AGREEMENT A2
 WHERE A2.VEHICLE_ID = V.VEHICLE_ID
 AND A2.Return_Date < stDate)**

如有任何帮助，我们将不胜感激。

Answer 1

您的 Sql 查询是一个内连接，因此在 Linq 中您可以:

var cars =  from v in db.VEHICLEs
            from a in db.AGREEMENTs
            from a1 in db.AGREEMENTs
            where a.CAR_ID == v.CAR_ID
                && enDate >= a.HIRE_START_DATE
                && strtDate <= a.HIRE_END_DATE
                && a1.CAR_ID == v.CAR_ID
                && location == a1.RETURN_LOCATION
                && a1.RETURN_DATE == db.AGREEMENTs
                    .Where(a2 => a2.VEHICLE_ID == v.VEHICLE_ID)
                    .Max(a2 => a2.RETURN_DATE)
            select v.CAR_ID;

要选择其他字段，您可以select new { CarId = v.CAR_ID, ... }