Linq查詢不返回數據

Question

我在SQL中有以下查詢，該查詢返回5行數據：

SELECT DISTINCT c.Id, c.FirstName, c.LastName, c.PhoneNumber, 'Waiting to be sent'
FROM DistributionGroupMembers dgm
JOIN Contacts c on dgm.ContactId = c.Id
JOIN DistributionGroups dg on dgm.DistributionGroupId = dg.Id
WHERE dg.Id IN (
    SELECT DistributionGroupId
    FROM DistributionGroupInSms
    WHERE SmsId = 40
)

當我嘗試使用LINQ在C＃中運行適當的查詢時，它將不會返回任何內容：

int[] groupIDs = await _db.DistributionGroupInSms.Where(dgis => dgis.SmsId == message.Id).Select(g => g.Id).ToArrayAsync();
var recipients = await (from dgm in _db.DistributionGroupMembers
                        join c in _db.Contacts on dgm.ContactId equals c.Id
                        join dg in _db.DistributionGroups on dgm.DistributionGroupId equals dg.Id
                        where groupIDs.Contains(dg.Id)
                        select new
                        {
                            ID = c.Id,
                            FN = c.FirstName,
                            LN = c.LastName,
                            PN = c.PhoneNumber,
                            SR = "Waiting to be sent"
                        }).Distinct().ToListAsync();

我究竟做錯了什么？

Answer 1

您可以簡單地加入：

int[] groupIDs = await _db.DistributionGroupInSms.Where(dgis => dgis.SmsId == message.Id).Select(g => g.Id).ToArrayAsync();
var recipients = await (from dgm in _db.DistributionGroupMembers
                        join c in _db.Contacts on dgm.ContactId equals c.Id
                        join dg in _db.DistributionGroups on dgm.DistributionGroupId equals dg.Id
                        join gIds in groupIDs on gIds equals dg.Id
                        select new
                        {
                            ID = c.Id,
                            FN = c.FirstName,
                            LN = c.LastName,
                            PN = c.PhoneNumber,
                            SR = "Waiting to be sent"
                        }).Distinct().ToListAsync();

Answer 2

我在select子句中通過獲取我選擇的Id而不是表中名為DistributionGroupId的另一個字段的groupIDs 。 謝謝大家的投入