How to use Linq to group DateTime by month and days calculation

Posted by Daoming Yang on Stack Overflow See other posts from Stack Overflow or by Daoming Yang
Published on 2010-04-09T17:03:34Z Indexed on 2010/04/09 17:13 UTC
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c#

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LINQ

Hi all, I have two questions:

First one:

I have a order list and want to group them by the created month for the reports.

Each order's created datetime will be like "2010-03-13 11:17:16.000"

How can I make them only group by date like "2010-03"?

Note: the DateCreated is the DateTime tpye

The following code is not correct.

var items = orderList.GroupBy(t => t.DateCreated.Month)
 .Select(g => new Order()
 {
     DateCreated = g.Key

 })
 .OrderByDescending(x => x.OrderID).ToList();

Second one: Output the full months between two dates in C#

If an user choose 2010-04-08 and 2010-06-04, I want to output the 2010-04-01 and 2010-06-30.

I can always get the first day and last day of the months, but I want to find out some other options

Many thanks.

Many thanks.

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