Question

根据登录用户的说法，我必须总结来自服务的数据。到目前为止，我已经达到了这个目的：

SummaryModel q = (from s in pe.Services
    join g in pe.Groups on s.GroupId equals g.GroupId
    join ud in pe.UserDetails on s.UserIdInCharge equals ud.UserId into ud1
        from ud in ud1.DefaultIfEmpty()
        where allowedGroups.Contains(g.GroupId)
        && (!filterBySector || filter.selectedSectors.Contains(g.GroupId))
        && (!filterByGroup || (s.UserIdInCharge.HasValue 
                               && members.Contains(s.UserIdInCharge.Value)))
        && (s.Status == (decimal)Data.Enums.ServiceStatus.Active 
            || s.Status == (decimal)Data.Enums.ServiceStatus.Sold)
        && s.ServiceStartDate >= startDate
        && s.ServiceStartDate <= endDate
        group s by new Guid() into services
        select new SummaryModel()
          { 
            Holes = services.Where(ss => ss.UserIdInCharge == null).Count(),
            Candidates = services.Sum(ss => ss.ServiceApplies.Count()),
            Announced = services.Where(ss => ss.AnnouncementType != 0).Count(),
            TotalServices = services.Count(),
            TotalHours = (decimal)services.Sum(ss => SqlFunctions
                      .DateDiff("hh", ss.ServiceStartDate, ss.ServiceEndDate)),
           TotalBudget = services.Sum(ss => ss.Value.Value),
          }).SingleOrDefault();

但下面的行返回：

TotalHours = (decimal)services.Sum(ss => SqlFunctions.DateDiff("hh",
                                   ss.ServiceStartDate, ss.ServiceEndDate)),

错误

LINQ to Entities无法识别 “System.Nullable 1[System.Int32] DateDiff(System.String, System.Nullable 1的System.DateTime] System.Nullable`1 [System.DateTime]）'，方法，它不能转换为存储库的表达。

日期样本

StartDate =＆gt; 05/09/2011 23:00:00
EndDate =＆gt; 06/09/2011 11:00:00

任何替代方案？

Answer 1

也许是这样的

var timeDifArray = (from s in pe.Services
    join g in pe.Groups on s.GroupId equals g.GroupId
    join ud in pe.UserDetails on s.UserIdInCharge equals ud.UserId into ud1
        from ud in ud1.DefaultIfEmpty()
        where allowedGroups.Contains(g.GroupId)
        && (!filterBySector || filter.selectedSectors.Contains(g.GroupId))
        && (!filterByGroup || (s.UserIdInCharge.HasValue 
                               && members.Contains(s.UserIdInCharge.Value)))
        && (s.Status == (decimal)Data.Enums.ServiceStatus.Active 
            || s.Status == (decimal)Data.Enums.ServiceStatus.Sold)
        && s.ServiceStartDate >= startDate
        && s.ServiceStartDate <= endDate
        group s by new Guid() into services
        select new
          { 
            services.ServiceStartDate,
            services.ServiceEndDate,
          }).ToArray();

var timeDifs = timeDifArray.Select(x => x.ServiceEndDate.Subtract(x.ServiceEndDate));
var totalTimeDifs = timDifs.Sum(x => x.Hours);

Answer 2

实际上发生的事情是VS正在使用System.Data.Entity.SqlServer.SqlFunctions代替System.Data.Objects.SqlClient.SqlFunctions。我强制命名空间，以便LINQ可以找到正确的函数集。

有没有办法在LINQ查询中Sum Sum SQLFunction.DateDiff？

2 个答案: