LINQ-can'；t创建请求

本文关键字：创建 请求 LINQ-can | 更新日期: 2023-09-27 17:59:16

你好，我有以下结构：

Table Countries:
- CountryID
- CountryName
Table Records:
- RecordID
- RecordName
- CountryID

此LINQ返回所有国家的列表"原样"：

 (from i in db.Countries 
 select new SelectListItem() 
 { 
     Text = i.CountryName, 
     Value = i.CountryID.ToString() 
 }).ToList();

我想把这个国家列表按这样的方式排序：在"记录"表中最受欢迎的国家排在最前面。怎么做？

LINQ-can'；t创建请求

您可以尝试类似的

(from i in db.Countries 
 join r in db.Records on i.CountryID equals r.CountryID into rds
 orderby rds.Count() descending
 select new SelectListItem() 
 { 
     Text = i.CountryName, 
     Value = i.CountryID.ToString() 
 }).ToList();

  var  recordsItem=db.Records.GroupBy(x=> x.CountryID).Select( gr => new{ CID=gr.Key, Count=gr.Count()}).ToList();
  var result= (from c in db.Countries
              join  r in  recordsItem on c.CountryID equals r.CID
              order by r.Count descending
              select  new  SelectListItem() 
               {
                  Text = c.CountryName, 
                  Value =   c.CountryID.ToString()
               }).ToList();
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