Question

I want to write a Linq to Sql query that does a count and groups by a Username and DateTime. I want the DateTime to be formatted like following ‘YYYY-MMM’ (i.e. 2009-Mar).

I thought this would work but Linq to Sql can’t parse the ToString ‘format’ argument.

            dc.MyTable               .GroupBy(r => new               {                   Name = r.UserName,                   YearMonth = r.SomeDateTime.ToString('yyyy-MMM')               })               .Select(r => new               {                   Name = r.UserName,                   YearMonth = r.YearMonth,                   Count = r.Count()               })               .OrderBy(r => r.YearMonth)               .ThenBy(r => r.Name); 

Does anyone have any thoughts/suggestions?

Thanks.

Answer 1

I wonder if you shouldn’t do that the ‘long’ way…

          dc.MyTable           .GroupBy(r => new           {               Name = r.UserName,               Year = r.SomeDateTime.Year,               Month = r.SomeDateTime.Month           })           .Select(r => new           {               Name = r.UserName,               Year = r.Year,               Month = r.Month,               Count = r.Count()           })           .OrderBy(r => r.Year)           .ThenBy(r => r.Month)           .ThenBy(r => r.Name); 

If you need the format as a string, do that later at the UI. Either by reconstructing a DateTime etc, or using CultureInfo.CurrentCulture.DateTimeFormat.GetMonthName(...).