DDD领域模型企业级系统（三）

相关代码：

public static void ShowArray()
        {
            //数据源
            int[] arrayas = new int[] { 1, 2, 3, 4 };
            //创建查询
            var query = from a in arrayas select a;

            foreach (var arraya in query)
            {
                Console.WriteLine(arraya.ToString());
            }
        }

        public static void ShowArrayWhere()
        {
            //数据源
            int[] arrayas = new int[] { 1, 2, 3, 4 };
            //创建查询
            var query = from a in arrayas where(a%2==1)
                        select a;

            foreach (var arraya in query)
            {
                Console.WriteLine(arraya.ToString());
            }
        }

        public static void ShowArrayCount()
        {
            //数据源
            int[] arrayas = new int[] { 1, 2, 3, 4 };
            //创建查询
            var query = from a in arrayas
                        where (a % 2 == 1)
                        select a;

            Console.WriteLine(query.Count());
        }

        public static void ShowArrayList()
        {
            int[] arrayas = new int[] { 1, 2, 3, 4 };
            var query = from a in arrayas
                        where (a % 2 == 1)
                        select a;
            var querList = query.ToList();
            foreach (var a in querList)
            {
                Console.WriteLine(a.ToString());
            }

        }

        public class Student
        {
            public string Name { get; set; }
            public string Classes { get; set; }
            public List<int> Scores { get; set; }
        }

        public static void CreateStudnet()
        {
            var students = new List<Student>()
            {
                new Student { Name="sunweiwei",Classes="classs1",Scores=
                new List<int> { 90,80,60 } },
                new Student {Name="shizhiwei",Classes="classs2",Scores=
                new List<int> { 80,56,77} }
            };
            //创建查询   1.查询所有的学生  2.复合查询   3.放入 匿名对象中
            var query = from s in students
                        from score in s.Scores
                        where s.Classes == "classs1" && score > 60
                        orderby score descending
                        select new { Name = s.Name, Score = score };

            foreach (var student in query)
            {
                Console.WriteLine(student.Name + " " + student.Score);
            }
        }

        /// <summary>
        /// 多个from查询
        /// </summary>
        public static void AndArray()
        {
            string[] arraya = new string[] { "aa", "bb" };
            string[] arrayb = new string[] { "cc", "dd" };

            var query = from a in arraya
                        from b in arrayb
                        select new { A=a, B=b };
            foreach (var s in query)
            {
                Console.WriteLine(s.A+""+s.B);
            }
        }

        /// <summary>
        /// Let
        /// </summary>
        public static void Let()
        {
            string[] arraya = new string[] { "aa", "bb" };

            var query = from a in arraya
                        let A = a.ToUpper()
                        select A;

            foreach (var s in query)
            {
                Console.WriteLine(s);
            }
        }

        public static bool mo(int a)
        {
            return a % 2 == 1;
        }

        public static void ShowArrayWhere1()
        {
            int[] arrayas = new int[] { 1, 2, 3, 4 };
            var query = from a in arrayas
                        where mo(a)
                        select a;
            foreach (var arraya in query)
            {
                Console.WriteLine(arraya.ToString());
            }
        }

        public static void CreateStudentOrderBy()
        {
            var students = new List<Student>()
            {
                new Student{ Name = "caojian", Classes = "classes1", Scores = new List<int> { 90, 80, 60 } },
                new Student { Name = "ligang", Classes = "classes2", Scores = new List<int> { 80, 56, 77 } }
            };
            var query = from s in students
                        from score in s.Scores
                        orderby score descending
                        select new { Name = s.Name, Score = score };
            foreach (var student in query)
            {
                Console.WriteLine(student.Name+"    "+student.Score);
            }
        }

        public static void CreateStudentCreateBy()
        {
            var students = new List<Student>()
            {
                new Student{ Name = "caojian", Classes = "classes1", Scores = new List<int> { 90, 80, 60 } },
                new Student { Name = "ligang", Classes = "classes2", Scores = new List<int> { 80, 56, 77 } }
            };
            var query = from s in students
                        from score in s.Scores
                            //存到范围变量中
                        group s by s.Classes into sclass
                        select sclass;
            foreach (var student in query)
            {
                Console.WriteLine(student.Key);
            }
        }

  public class ProductCategory
        {
            public int CID { get; set; }
            public string CName { get; set; }
        }

        public class Product
        {
            public int PID { get; set; }
            public string PName { get; set; }
            public int CID { get; set; }
        }

        public static void CreateCP()
        {
            var pcs = new List<ProductCategory>
            {
                new ProductCategory{ CID=1,CName="c1"}
            };
            var ps = new List<Product>
            {
                new Product{ PID=1,PName="p1",CID=1},
                new Product{ PID=2,PName="p2",CID=1}
            };
            var query = from c in pcs
                        join p in ps on c.CID equals p.CID
                        select new { CName = c.CName, PName = p.PName };
            foreach (var pc in query)
            {
                Console.WriteLine(pc.CName+"  "+pc.PName);
            }
        }

        public static void CreateCPGroup()
        {
            var pcs = new List<ProductCategory>
            {
                new ProductCategory{ CID=1,CName="c1"}
            };
            var ps = new List<Product>
            {
                new Product{ PID=1,PName="p1",CID=1},
                new Product{ PID=2,PName="p2",CID=1}
            };

            var query = from c in pcs
                        join p in ps on c.CID equals p.CID into pps
                        select new { CName = c.CName, pps };
            foreach (var pc in query)
            {
                foreach (var p in pc.pps)
                {
                    Console.WriteLine(pc.CName + "  " + p.PName);
                }
            }
        }

 public  class LinqToObject
    {
        public class Student
        {
            public string Name { get; set; }
            public string Classes { get; set; }
            public List<int> Scores { get; set; }
        }

        public static void CreateStudnet()
        {
            var students = new ArrayList()
            {

                new Student { Name="sunweiwei",Classes="classs1",Scores=
                new List<int> { 90,80,60 } },
                new Student {Name="shizhiwei",Classes="classs2",Scores=
                new List<int> { 80,56,77} }
            };
            //创建查询   1.查询所有的学生  2.复合查询   3.放入 匿名对象中
            var query = from Student s in students
                        from score in s.Scores
                        where s.Classes == "classs1" && score > 60
                        orderby score descending
                        select new { Name = s.Name, Score = score };

            foreach (var student in query)
            {
                Console.WriteLine(student.Name + " " + student.Score);
            }
        }

        public static List<Student> CreateStudentLamda()
        {
            var students = new List<Student>
            {
                new Student { Name="sunweiwei",Classes="classs1",Scores=
                new List<int> { 90,80,60 } },
                new Student {Name="shizhiwei",Classes="classs2",Scores=
                new List<int> { 80,56,77} }
            };
            //  var query = students.Where(p => p.Classes == "classs1").OrderBy(p => p.Classes).GroupBy(p => p.Classes);
            var query = students.Where(p => p.Classes == "classs1");
            //var query = students.Where(p => p.Classes == "classs1").Select(p => p.Classes.ToUpper());
            return query.ToList();

        }

        public static Student CreateStudentLamdal()
        {
            var students = new List<Student>
            {
                new Student { Name="sunweiwei",Classes="classs1",Scores=
                new List<int> { 90,80,60 } },
                new Student {Name="shizhiwei",Classes="classs2",Scores=
                new List<int> { 80,56,77} }
            };
            //  var query = students.Where(p => p.Classes == "classs1").OrderBy(p => p.Classes).GroupBy(p => p.Classes);
            var query = students.Where(p => p.Classes == "classs1").SingleOrDefault();

            return query;

        }
    }

 private void btnshowstudent_Click(object sender, EventArgs e)
        {
            var studens = LINQObject.LinqToObject.CreateStudentLamda();
            dgstudents.DataSource = studens;

        }