LINQ到实体查询-组中重复

Question

I have the following table that holds a list of shifts and the user assigned to each of those shifts as below:

ShiftID | StartDateTime | EndDateTime | AssignedUserID |
-------------------------------------------------------------

What I am trying to do is pull out the shiftID for all shifts that have been assigned to a user on the same date and time. This should not happen as a person cannot be in two places at once...(this one has been sorted...now)

We have some instances in our database where the same user has been assigned to work on 2 different shifts on the same date and time.

eg

56 | 06/08/2015 13:00:00 | 06/08/2015 17:00:00 | 22

64 | 06/08/2015 13:00:00 | 06/08/2015 17:00:00 | 22

Hope someone can help with this, even as a start to pull out the users who have been assigned to shifts on the same start date ?

public IList<ShiftDate> GetDuplicateShifts()
{
    return _UoW.ShiftDate.Get()
        .ToList();
}

UPDATE

OK, I'm getting there, I am now able to pull out all groups of users where the user is on 2 dates on the same day, the code below works:

public IList<ShiftDate> GetDuplicateShiftsByOrg(int orgID)
{
    IList<ShiftDate> AllDates = _UoW.ShiftDates
        .Get(s => s.Shift.organisationID == orgID)
        .Where(s=>s.assignedUserID != null)
        .ToList();

    var DuplicateDates = new List<ShiftDate> { };

    var groups = AllDates.GroupBy(s=>s.assignedUserID.Value).Where(g => g.Skip(1).Any());

    foreach (var group in groups)
    {
        var group2 = group.GroupBy(sd => sd.shiftStartDate.Date).Where(a => a.Count() > 1).ToList();

        if (group2.Count() > 1)
        {


        ///// REF 1 : this pulls out all shiftdates in group one, I want all shiftdates in group2.

            foreach (ShiftDate shiftDate in group)
            {
                    DuplicateDates.Add(shiftDate);
            }

/////////////////////////////////////////////////////////

        }
    }

    return DuplicateDates.ToList();
}

As you will see at REF one above in the code I want to pull out the shiftdates in group2. However when I try to do this I get the following error:

Unable to cast object of type 'Grouping[System.DateTime,MySolution.POCO.ShiftDate]' to type 'MySolution.POCO.ShiftDate'.

UPDATE

The error above was appearing because I was trying to return a shiftdate from a group of shift dates, I had to add an extra loop to cycle through the groups first. See solution below

Answer 1

try this:

var dt=DateTime.Now().ToString("MM/dd/yyyy"); 
var result = from t in Table1
WHERE c.StartDate=dt
SELECT new {c.AssignedUserID};

Answer 2

Finally got this working by using multiple groups, see working code below:

 public IList<ShiftDate> GetDuplicateShiftsByOrg(int orgID)
    {
        IList<ShiftDate> AllDates = _UoW.ShiftDates
            .Get(s => s.Shift.organisationID == orgID)
            .Where(s=>s.assignedUserID != null)
            .ToList();

        var DuplicateDates = new List<ShiftDate> { };

        /// 1. Group all shifts assigned to user
        var groupUserShifts = AllDates.GroupBy(s=>s.assignedLocumID.Value).Where(g => g.Skip(1).Any());

        foreach (var group in groupUserShifts)
        {
            /// 2. Group all shifts assigned to user on the same date
            var groupUserSameDates = group.GroupBy(sd => sd.shiftStartDate.Date).Where(a => a.Count() > 1).ToList();


            if (groupUserSameDates.Count() > 1)
            {
                foreach (var dategroup in groupUserSameDates)
                {
                    /// 3. Return all shifts where user hass been assigned on the same date
                    foreach (ShiftDate shiftDate in dategroup)
                    {
                        DuplicateDates.Add(shiftDate);
                    }
                }
            }
        }

        return DuplicateDates.ToList();
    }