c# - 使用 DbFunctions 返回包含分钟的日期时间

Question

我有以下代码，它会截断时间:

// 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

我尝试过使用简单的东西，比如字符串比较，但你不能在 Linq-to-Entities 内部这样做:

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

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();