使用 DbFunctions return 包含分钟的日期时间

Question

我有以下代码，它截断了时间：

// does this already exist? 
var seekScan = (from s in aDb.Item_Scan_Event
                where s.item_detail_id == th_piece_id &&
                      s.scan_type == scantype &&
                      DbFunctions.TruncateTime(s.scan_datetime) == dt_scan.s.ScanDatetime.Date
                select s).FirstOrDefault();

我需要的是让它比较日期时间，包括 HH:mm

我试过使用一些简单的东西，比如字符串比较，但你不能在 Linq-to-Entities 中这样做：

var seekScan = (from s in aDb.Item_Scan_Event
                where s.item_detail_id == th_piece_id &&
                      s.scan_type == scantype &&
                      s.scan_datetime.Value.ToString("MM/dd/yyyy HH:mm") == dt_scan.s.ScanDatetime.ToString("MM/dd/yyyy HH:mm")
                select s).FirstOrDefault();

我得到的错误是：

LINQ to Entities does not recognize the method 'System.String ToString(System.String)' method, and this method cannot be translated into a store expression.'

Answer 1

看看这个FUNCTION database.AddDays does not exist

在 Mysql 我要创建函数，也许你需要在你的 bd 中查看函数。

Answer 2

不优雅，但有效。

//does this already exist?  Ignore items scanned within the same minute.
var seekScan = (from s in aDb.Item_Scan_Event
        where
        s.item_detail_id == th_piece_id &&
        s.scan_type == scantype &&
        (s.scan_datetime.Value.Year == dt_scan.s.ScanDatetime.Year &&
        s.scan_datetime.Value.Month == dt_scan.s.ScanDatetime.Month &&
        s.scan_datetime.Value.Day == dt_scan.s.ScanDatetime.Day &&
        s.scan_datetime.Value.Hour == dt_scan.s.ScanDatetime.Hour &&
        s.scan_datetime.Value.Minute == dt_scan.s.ScanDatetime.Minute )
        select s
    ).FirstOrDefault();

Answer 3

简化并使用 DbFunctions class :

var seekScan = (from s in aDb.Item_Scan_Event
        where
        s.item_detail_id == th_piece_id &&
        s.scan_type == scantype && (
        DbFunctions.TruncateTime(s.scan_datetime.Value).Value == dt_scan.s.ScanDatetime.Date &&
        DbFunctions.DiffMinutes(s.scan_datetime.Value, dt_scan.s.ScanDatetime) == 0 )
        select s
    ).FirstOrDefault();

更新

We could just use the DiffMinutes and that would work unless it was that exact same time and a different day ?

时间跨度相同但日期不同的情况会失败

does DiffMinutes ignore the date portion ? So 11/11/2019 11:02 vs 11/12/2019 11:03 would be 1 ?

我不确定 returns 日期和时间跨度之间的差异还是只是时间跨度，我已经很久没有使用它了。我猜你会测试它并告诉我们。

Answer 4

当您定义类型为 Datetime 的属性时，如果默认情况下没有为属性定义属性，它将保存时间，包括小时、分钟和秒。

所以根据以下情况是一些用例：

场景 1：仅检查 day/month/year

a) 对于日期时间

var loRecords = context.ORDERS.Where(x=>x.O_ORDER_TIME.Date.Equals(DateTime.Now.Date).ToList()

b) 对于日期时间？

 var loRecords = context.ORDERS.Where(x=>x.O_ORDER_TIME?.Date.Equals(DateTime.Now.Date).ToList()

场景 2：检查 day/month/year 小时和分钟

a) 日期时间

var loRecords = context.ORDERS.Where(x=>x.O_ORDER_TIME.Date.Equals(DateTime.Now.Date) 
&& x.O_ORDER_TIME.Date.Hour == DateTime.Now.Date.Hour
&& x.O_ORDER_TIME.Date.Minute == DateTime.Now.Date.Minute).ToList()

使用 DbFunctions return 包含分钟的日期时间

Use DbFunctions to return the dateTime with mins included

c#

entity-framework-6