Question

I have two tables: Category (Id, Name, ...) and Question (Id, CategoryId, Title, ...) with relation Category 1-* Question. I need to get the top three categories (with the highest number of questions) from the database.
I wrote this SQL query:

SELECT TOP 3 c.Name, COUNT(q.CategoryId)
FROM Category c
JOIN Question q
ON c.Id = q.CategoryId
GROUP BY Name
ORDER BY COUNT(q.CategoryId) DESC

and of course it works, but I need to write this query in LINQ. The main problem is in the first line with COUNT. How should I use it in this query?

Answer 1

I’m not sure where your data comes from but the query will look something like

var q =
    from c in categories
    join q in questions on c.Id equals q.CategoryID
    group c by c.Name into g 
    orderby g.Count() descending
    select new
    {
        Name = g.Key,
        Count = g.Count()
    };

 q = q.Take(3);