How to combine Where clause and group by in LINQ

Question

Can any one help me convert the below code to LINQ?

Select Catg,Count(*)  From Mycatg  where IsPublic=1 or FirstName='XXX' Group By Catg  .

Answer 1

In C#, something like:

var query = from category in mycatg
            where category.IsPublic == 1
               || category.FirstName == "XXX"
            group 1 by category.Catg into grouped
            select new { Catg = grouped.Key,
                         Count = grouped.Count() };

The projection of "1" makes it clear that all we need is the key of the grouping and the count - the individual entries in each grouping are irrelevant.

Using lambda syntax and dot notation:

var query = mycatg.Where(category => category.IsPublic == 1
                         || category.FirstName == "XXX")
                  .GroupBy(category => category.Catg,
                           category => 1)
                  .Select(grouped => new { Catg = grouped.Key,
                                           Count = grouped.Count() });