How to calculate count on of table column using group by clause in linq - asp.net

Question

I'm new to linq.
In c# I'm doing as follows to get the count of one column.
SELECT DispatcherName,
ActivityType,
CONVERT(BIGINT,COUNT(ActivityType)) AS Total
FROM ACTIVITYLOG
GROUP BY DispatcherName,
ActivityType
ORDER BY Total DESC
Can any one tell m,how I can achieve the same thing using LINQ.
Update:
HI I did as follows and got the reslut.
But I'm not able to convert result to datatable.
this is how I did.
here dt is datatabe with two columns Dispatchername and ActivityType.
var query1 = from p in dt.AsEnumerable()
group p by new
{
DispatcherName = p.Field<string>("Dispatchername"),
Activity = p.Field<string>("ActivityType"),
}
into pgroup
let count = pgroup.Count()
orderby count
select new
{
Count = count,
DispatcherName = pgroup.Key.DispatcherName,
Activity = pgroup.Key.Activity
};
pls help me out asap.

Answer 1

from c in ACTIVITYLOG
group c by new {c.DispatcherName, c.ActivityType} into g
orderby g.Count() descending
select new { g.Key.DispatcherName, g.Key.ActivityType, Total = g.Count() }

Answer 2

If you want your results returned back to a DataTable, one option is to use the CopyToDataTable method.
Here's a live example: http://rextester.com/XHX48973
This method basically requires you to create a dummy table in order to use its NewRow method - the only way to create a DataRow, which is required by CopyToDataTable.
var result = dt.AsEnumerable()
.GroupBy(p => new {
DispatcherName = p.Field<string>("DispatcherName"),
Activity = p.Field<string>("ActivityType")})
.Select(p => {
var row = dummy.NewRow();
row["Activity"] = p.Key.Activity;
row["DispatcherName"] = p.Key.DispatcherName;
row["Count"] = p.Count();
return row;
})
.CopyToDataTable();
Perhaps a better way might be just fill in the rows directly, by converting to a List<T> and then using ForEach.
DataTable dummy = new DataTable();
dummy.Columns.Add("DispatcherName",typeof(string));
dummy.Columns.Add("Activity",typeof(string));
dummy.Columns.Add("Count",typeof(int));
dt.AsEnumerable()
.GroupBy(p => new { DispatcherName = p.Field<string>("DispatcherName"),
Activity = p.Field<string>("ActivityType")})
.ToList()
.ForEach(p => {
var row = dummy.NewRow();
row["Activity"] = p.Key.Activity;
row["DispatcherName"] = p.Key.DispatcherName;
row["Count"] = p.Count();
dummy.Rows.Add(row);
});
Live example: http://rextester.com/TFZNEO48009

Answer 3

This should do the trick:
IList<ACTIVITYLOG> allActivityLogs;
var result = (from c in allActivityLogs
select new
{
DispatcherName = c.DispatcherName,
ActivityType = c.ActivityType,
Total = c.ActivityType.Count
}).OrderByDescending(x => x.Total)
.GroupBy(x => new { x.DispatcherName, x.ActivityType });
You only need to substitute the allActivityLogs collection with the actual collection of your entities.