C# 带计数的LINQ-Lamba连接

我想得到所有没有当前球队的球队，以及所有有4名或更多球员的球队。 我尝试编写以下linq lambda查询：

teams = connection.Team 
    .Join(connection.Player,
        t => t.ID,
        p => p.IDTeam,
        (t, p) => new { Team = t, Player = p })
    .Where(tp => tp.Player.IDTeam == tp.Team.ID
        && tp.Team.ID != team.ID
        && tp.Team.IsVisible == true
        && !tp.Team.DeleteDate.HasValue)
    .Select(tp => tp.Team)
    .ToList();

但我不能指望在什么情况下有多少球员参加比赛。如何做？对于信息，这是SQL中的查询？ 谢谢你的帮助

编辑： 根据需要，类（从DBFirst生成）：

---

基于上述类，您可以扩展

团队

类并添加

玩家

导航属性

添加导航属性时，请确保团队和玩家表之间存在数据库关系。此外，如果需要，请配置

DbContext

public class Team
{
    //...other properties
    public virtual ICollection<Player> Players { get; set; }
}

尝试一个GroupBy（）：

试试这个：

teams = connection.Team 
.Join(connection.Player,
    t => t.ID,
    p => p.IDTeam,
    (t, p) => new { Team = t, Player = p })
.Where(tp => tp.Player.IDTeam == tp.Team.ID
    && tp.Team.ID != team.ID
    && tp.Team.IsVisible == true
    && !tp.Team.DeleteDate.HasValue)
.Select(tp => tp.Team)
.ToList().GroupBy(i=>i.ID).Where(i=>i.Count()>=4);

这个怎么样

var teams = 
           (from t in connection.Team
           join p in connection.Player on p.TeamId equals t.ID into playersInTeam
           select new 
           { 
                Team = t, 
                PlayersCount = playersInTeam.Count(x => x.TeamId == t.Id) 
           })
           .Where(x => x.PlayersCount >= 4)
           .ToList();

---

DarjanBogdan补充道：“你没有导航属性吗？你能提供玩家和团队等级吗？”。没有Tim，任何导航属性Thanks@MicheleBoscagin：我很确定

Player.IdTeam

到

Team.Id

上没有外键。修复此问题，实体框架将添加此导航属性。我想没有外键，这就是实体框架没有自动创建的原因。@TimSchmelter是的，可能就是这样

teams = connection.Team 
.Join(connection.Player,
    t => t.ID,
    p => p.IDTeam,
    (t, p) => new { Team = t, Player = p })
.Where(tp => tp.Player.IDTeam == tp.Team.ID
    && tp.Team.ID != team.ID
    && tp.Team.IsVisible == true
    && !tp.Team.DeleteDate.HasValue)
.Select(tp => tp.Team)
.ToList().GroupBy(i=>i.ID).Where(i=>i.Count()>=4);

var teams = 
           (from t in connection.Team
           join p in connection.Player on p.TeamId equals t.ID into playersInTeam
           select new 
           { 
                Team = t, 
                PlayersCount = playersInTeam.Count(x => x.TeamId == t.Id) 
           })
           .Where(x => x.PlayersCount >= 4)
           .ToList();