DbFunction.DiffMinutes { 'System.NotSupportedException' }

Question

我想写这段代码我的这部分代码

    var today = DateTime.Now;
    var todayString = today.ToShortDateString();
    List<FB> fBList = _context.FBs.ToList();
    fBList = fBList.Where(x => DbFunctions.DiffMinutes(x.FB_CDate, x.FB_LTDate) > 20 ).ToList();

这部分 return 我这个

    'DbFunctions.DiffMinutes(x.FB_CDate, x.FB_LTDate) > 20' threw an exception of type 'System.NotSupportedException'

Answer 1

DbFunctions 提供 CLR 方法，当在 LINQ to Entities 查询中使用时，这些方法会转换为 数据库函数 。当您调用 ToList() 时，数据被加载到内存中并且 DbFunctions 导致错误。您需要按如下方式更改代码：

 var today = DateTime.Now;
            var todayString = today.ToShortDateString();
            List<FB> fBList = _context.FBs.Where(x => DbFunctions.DiffMinutes(x.FB_CDate, x.FB_LTDate) > 20).ToList();

DbFunction.DiffMinutes { 'System.NotSupportedException' }

DbFunction.DiffMinutes { 'System.NotSupportedException' }

c#

linq

entity-framework

notsupportedexception

dbfunctions