将SQL查询与组转换为LINQ

Question

I have the below sql query that i am able to conert into LINQ

select count(*), BatchID 
from TimeSheetHeader 
group by BatchID having count(*) > 1

converts to

var duplicateBatchIDList = from c in _db.TimeSheetHeaders
                                               group c by c.BatchID into grp
                                               where grp.Count() > 1
                                               select grp;

But now i am trying to throw an extra column that isnt included in the group by. I have the SQL query

select count(*), BatchID, TimeSheetCreationDate = min( TimeSheetCreationDate     ) 
from TimeSheetHeader 
where TimeSheetCreationDate >= CURRENT_TIMESTAMP
group by BatchID having count(*) > 1

But i am not sure how this convert over to LINQ

Answer 1

from c in _db.TimeSheetHeaders
where c.TimeSheetCreationDate >= CURRENT_TIMESTAMP
group c by c.BatchID into grp
where grp.Count() > 1
select new
{
    BatchID = grp.Key,
    Count = grp.Count(),
    TimeSheetCreationDate = grp.Min(x => x.TimeSheetCreationDate)
}

Answer 2

Here you can find the lambda expression version of the query:

var result = TimeSheetHeader
    .Where(t => t.TimeSheetCreationDate >= TIMESTAMP)
    .GroupBy(t => t.BatchID)
    .Where(g => g.Count() > 1)
    .Select(g => new 
        {
            Count = g.Count(),
            BatchID = g.Key,
            TimeSheetCreationDate = g.Min(x => x.TimeSheetCreationDate)
        })
    .ToList();

Answer 3

I slightly modified Magnus's answer

var duplicateBatchIDList = (from c in _db.TimeSheetHeaders
                                               group c by c.BatchID into grp
                                               where grp.Count() > 1
                                               select new
                                               {
                                                   BatchID = grp.FirstOrDefault().BatchID,                                                      
                                                   TimeSheetCreationDate = grp.Min(x => x.TimeSheetCreationDate)
                                               }).Where(x => x.TimeSheetCreationDate <= DateTime.Now);