如何 select 使用实体框架在相关表中重复最多的记录

Question

My tables here:

In C#

I want to know most repeated 3 categoryName and their count in Blog table, any idea? Thanks

Answer 1

var result = blogs.GroupBy(b => b.CategoryID)
            .OrderByDescending(g => g.Count())
            .Take(3)
            .Select(x => new {CategoryName = x.First().Category.CategoryName, Count = x.Count()})
            .ToList();

This will group your blogs by CategoryID, order by count of each grouping, take the top 3 and then select the category name and count of each group as a list.

Answer 2

list.GroupBy(x => x.CategoryName).Select(x => new { x.Key, count = x.Count() }).OrderBy(x => x.count).Take(3);

This will first Group the items by the name. Then create an anonymous object with the group key (the name) and the Count of all items in every group. Then you order by count and take the first 3.

Answer 3

You could group by category name, order by highest count first and pick the first three results. Example:

Blogs
    .GroupBy(b => b.Category.CategoryName) 
    .OrderByDescending(g => g.Count())
    .Take(3)
    .Select(x => new { CategoryName = x.Key, Count = x.Count() });