Selecting count in LINQ

Question

I got a SQL Server table with columns ResolvedDate and ResolvedBy.

Now I want to select those two columns and count their results, which I

Answer 1

If you're trying to count each item by date, you'd need to use GroupBy:

var countsByDate = _dateContext.Activities
                           .Where(a => a.IsResolved && a.ResolvedBy == userId)
                           .GroupBy(a => a.ResolvedDate)
                           .Select(g => new {ResolvedDate = g.Key, Count = g.Count() });

Answer 2

var dates = dataContext.Activities
    .Where(a => a.IsResolved && a.ResolvedBy == userId)
    .Select(a => a.ResolvedDate)
    .ToList();

var count = dates.Count;

If you only want to get the count, you can make it much faster by selecting the count alone:

var count = dataContext.Activities
    .Count(a => a.IsResolved && a.ResolvedBy == userId);

Answer 3

You have to group your data by ResolvedDate to get number of activities resolved every day.

var dates = from a in dataContext.Activities
            where a.IsResolved && a.ResolvedBy == userId
            group a by a.ResolvedDate into g
            select new { Date = g.Key, Count = g.Count() }

To group just by day (without hour, minutes, etc.) you can change the group statement:

var dates = from a in dataContext.Activities
            where a.IsResolved && a.ResolvedBy == userId
            group a by a.ResolvedDate.Date into g
            select new { Date = g.Key, Count = g.Count() }

Answer 4

from a in dataContext.Activities
where a.IsResolved && a.ResolvedBy == userId
group a by a.ResolvedDate into g
select new {ResolvedOn=g.Key, NumberResolved= g.Count()}