我尝试在实体框架中使用DateDiff：

var data = (from e in _context.Employers
            join t in _context.Tickets on e.Id equals t.IdEmployer
            join i in _context.InfoClients on t.IdConnexion equals i.Id
            where t.Etat == "Encours"
            select new
                   {
                       t.DateCreation,
                       t.NumTicket,
                       i.IdConnexion,
                       datediff = DateTime.Now.Subtract((DateTime)t.DateCreation).TotalDays,
                       t.SujetPrblm,
                       t.IdTicket,
                       e.Nom,
                       e.Prenom
                   }).ToList();

但我得到这个错误：
只能从链接到实体调用此函数
我也尝试了这个，但得到相同的错误：

DateDiff = SqlFunction.DateDiff("Hour", t.DateCreation, DateTime.Now)