[英]How to get the last not logged-in user's within three weeks backwards?
我正在嘗試獲取過去三周內未登錄的用戶。 我聽說過要使用的方法 Min 和 Max,但不確定如何使用。 所以我想獲取過去三周未登錄的用戶,其中LoginDate
是用戶日志列表:
var threeWeeksAgo = DateTime.Now.Date.AddDays(-21);
//userLogins is a table
var lastLogins = lowUsers.UserLogins
.Join(lowUsers.Clients, ul => ul.client, c => c.companyName, (ul, c) => new { ClientId = c.clientID, LoginDate = ul.dateTimeCreated, CompanyName = c.companyName })
.Where(a => a.LoginDate <= threeWeeksAgo);
如何使用過去三周未登錄的用戶列表檢查 LoginDate。
數據:
Id UserName LoginDate
1 User1 01/10/2021 13:24
2 User2 02/09/2021 13:24
3 User1 03/10/2021 13:24
4 User1 04/10/2021 13:24
5 User2 03/09/2021 13:24
如果LoginDate
是DateTime
類型,您可以執行以下操作
var threeWeeksAgo = DateTime.Now.AddDays(-21);
//userLogins is a table
var notLoggedInUsers = userLogins.Where(a=>a.LoginDate < threeWeeksAgo).ToList();
您需要先按客戶分組,為該組的日期排序,然后將上次登錄日期與三周前進行比較。
var threeWeeksAgo = DateTime.Now.Date.AddDays(-21);
//userLogins is a table
var lastLogins = lowUsers.UserLogins
.Join(lowUsers.Clients, ul => ul.client, c => c.companyName, (ul, c) => new { ClientId = c.clientID, LoginDate = ul.dateTimeCreated, CompanyName = c.companyName })
.GroupBy(x => x.ClientId)
.Select(g => new { ClientId = g.Key, LastLoginDate = g.OrderByDescending(x => x.LoginDate).FirstOrDefault()?.LoginDate})
.Where(a => a.LastLoginDate <= threeWeeksAgo);
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