Question

我简要地说这些表格：

表：RPG

Coloumns：RPGID，姓名

表：RPGCharacter

Coloumns：CharID，RPGID，姓名

表：RPGPosts

Coloumns：PostID，CharID，Text，timestamp

所以在数据库中关系是： 1个RPG有X个字符，1个字符有X个帖子。

我通过以下代码获取信息：

  public static List<RPG> GetAllRPGs()
    {
        using (RPGDataContext dc = new RPGDataContext())
        {
            return (from a in dc.RPGs where !a.IsHided && !a.IsDeleted select a).ToList();
        }
    }

问题是：如何按最后一篇文章（RPGPOst-Table的TIMESTAMP-Coloumn）对这些列表进行排序？

Answer 1

假设您已经设置了适当的导航属性，那么这样的事情应该有效：

var results = 
    (from a in dc.RPGs 
     where !a.IsHided && !a.IsDeleted 
     orderby a.Characters.SelectMany(c => c.Posts).Select(p => p.Timestamp).Max()
     select a)
    .ToList();

或者可能：

var results = 
    (from a in dc.RPGs 
     where !a.IsHided && !a.IsDeleted 
     orderby a.Characters
              .SelectMany(c => c.Posts)
              .OrderByDescending(p => p.Timestamp)
              .Select(p => p.Timestamp)
              .FirstOrDefault()
     select a)
    .ToList();

如何在linq to sql中为连接表排序？

1 个答案: