如何將sql與count轉換爲linq

Question

如何將其轉換爲linq？

select i.CatName,COUNT(*) as n_items 
from ixcxs i 
group by i.CatName 

或lambda表達式將有助於

Answer 1

嘗試

ixcxs.GroupBy(g => g.CatName) 
    .Select(s => new 
    { 
     CatName = s.Key, 
     n_items = s.Count() 
    }); 

在查詢語法

同樣的事情：

from i in ixcxs 
group i by i.CatName into g 
select new 
{ 
    CatName = g.Key, 
    n_items = g.Count() 
} 

Answer 2

你並不需要從組中選擇第一項獲取CatName - 使用分組密鑰代替：

var query = from i in ixcxs 
      group i by i.CatName into g 
      select new { 
       CatName = g.Key, 
       n_items = g.Count() 
      }; 

同樣的，方法的語法：

var query = ixcxs.GroupBy(i => i.CatName) 
       .Select(g => new { CatName = g.Key, n_items = g.Count() });