帮助Linq表达式根据字段计数返回字符串列表

Question

Say I have a table Comments with these columns: Id, Comment, Category, CreatedDate, CommenterId

I want to get the top 5 categories from the Comments table (based on the count of each category in that table). How can I do this in linq, to return either List or IQueryable?

Answer 1

You can use something like this:

var query = comments
    .GroupBy(comment => comment.Category)
    .OrderByDescending(g => g.Count())
    .Select(g => g.Key)
    .Take(5);

Answer 2

Try something like this:

var topComments = from comment in Comments
                  group comment by comment.Category into grp
                  orderby grp.Count() descending
                  select grp.Key;

var topFive = topComments.Take(5);