如何将sql与count转换为linq

Question

如何将其转换为linq？

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

或lambda表达式将有助于

Answer 1

尝试

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

在查询语法

同样的事情：

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

Answer 2

你并不需要从组中选择第一项获取CatName - 使用分组密钥代替：

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

同样的，方法的语法：

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