Combination of Linq groups and linq groups

Combination of Linq groups and linq groups

There is a List, which requires grouping by date and combining the data of the same day with the implementation of Linq.

namespace ConsoleApplication1{    class Program    {        static void Main(string[] args)        {            List<Student> students = new List<Student>()            {                new Student(){ ID = 1 , Name ="guwei1", BirthDay=DateTime.Now.AddHours(-11), Phone="123456781"},                new Student(){ ID = 2 , Name ="guwei2", BirthDay=DateTime.Now.AddHours(2).AddDays(2), Phone="123456782"},                new Student(){ ID = 3 , Name ="guwei3", BirthDay=DateTime.Now.AddHours(-13), Phone="123456783"},                new Student(){ ID = 4 , Name ="guwei4", BirthDay=DateTime.Now.AddHours(4).AddDays(4), Phone="123456784"},            };            var result = from p in students                         group p by p.BirthDay.ToString("yyyy-MM-dd") into g                         let q = students.Where(x => x.BirthDay.ToString("yyyy-MM-dd") == g.Key)                         select new                         {                             ID = q.Select(y => y.ID),                             Name = q.Select(y => y.Name),                             BirthDay = g.Key,                             Phone = q.Select(y => y.Phone),                         };            foreach (var item in result)            {                Console.WriteLine("ID:{0} Name:{1} BirthDay:{2} Phone:{3}",                    string.Join(",", item.ID),                    string.Join(",", item.Name),                    item.BirthDay,                    string.Join(",", item.Phone));            }        }    }    public class Student    {        public int ID { get; set; }        public string Name { get; set; }        public DateTime BirthDay { get; set; }        public string Phone { get; set; }    }}

We can see that the data items are grouped by date, and the data items of other attributes are merged and displayed.