Linq问题他求教

[倒大霉的上帝]

现有类如下：

 public class TestClass
    {
        public string userName { get; set; }
        public int Age { get; set; }
        public string QQCode { get; set; }
    }

代码如下

List<TestClass> tests = new List<TestClass>();
            tests.Add(new TestClass { userName = "张三", Age = 12, QQCode = "11111" });
            tests.Add(new TestClass { userName = "张三", Age = 12, QQCode = "22222" });
            tests.Add(new TestClass { userName = "李四", Age = 13, QQCode = "33333" });
            tests.Add(new TestClass { userName = "李四", Age = 13, QQCode = "44444" });
            tests.Add(new TestClass { userName = "李四", Age = 13, QQCode = "55555" });
            tests.Add(new TestClass { userName = "王五", Age = 14, QQCode = "66666" });
            tests.Add(new TestClass { userName = "赵六", Age = 15, QQCode = "77777" });

            var v = from p in tests 
                    group p by p.userName into g 
                    select new { 
                                    userName =g.Key,
                                    Count=g.Count() ,
                                    QQCodes=???
                                };

在QQCodes处 我想得到同一个的所有QQ集合，比如张三，就应该是"11111,22222" 李四就是"33333,44444,55555" 这里的代码应该怎么写了？

[threenewbee]

QQCodes = string.Join(",", g.Select(y => y.QQCode.ToString()))

[EnForGrass]

 var v = from p in tests 
                    group p by p.userName into g 
                    select new { 
                                    userName =g.Key,
                                    Count=g.Count() ,
                                    QQCodes = string.Join(",", g.Select(y => y.QQCode.ToString()).ToArray())
                                };
//或者下面这样
            var v1 = tests.GroupBy(p => p.userName).Select(p => new {
                userName = p.Key, 
                Count = p.Count(), 
                QQCodes = string.Join(",", p.Select(y => y.QQCode.ToString()).ToArray())
            });

[Hauk]

            var result = from tc in tests where tc.userName == "李四" select tc.QQCode;
            string qqCodes = string.Join(",", result.ToArray());

[Hauk]

var result = tests.Where(tc => tc.userName == "李四").Select(qq => qq.QQCode);
string qqCodes = string.Join(",", result.ToArray());

或者这样也可以