學習計劃實踐
阿新 • • 發佈：2018-12-14
static void Main(string[] args) { #region MyRegion //新增資料 //using (var db = new TestEFEntities()) //{ // db.Students.Add(new Student // { // Name = "lv22", // Sex = "2" // });// db.SaveChanges(); //} ////查詢 //using (var s_select = new TestEFEntities()) //{ // s_select.Database.Log = s => Console.WriteLine(s); // var st = s_select.Students.First(s => s.Id == 6); // //var m_student= s_select.Students.Select(u=>new { id = u.Id ,name=u.Name,sex=u.Sex}).FirstOrDefault();//} //刪除 //using (var db = new TestEFEntities()) //{ // //例項化一個物件，並指定ID的值 // var n = new Student() { Id = 4 }; // //將n物件附到上下文當中 // db.Students.Attach(n); // //刪除n物件 // db.Students.Remove(n);// db.SaveChanges(); // Console.WriteLine("刪除成功"); // //1.1 先根據id查詢 出 要刪除的 物件（存入EF容器） // Student usr = db.Students.Where(u => u.Id == 1).FirstOrDefault(); // //1.2 將實體物件刪除（就是將 容器中的 代理物件的 State改成 Deleted） // db.Students.Remove(usr); // //1.3 將EF容器裡所有的物件 根據 State 屬性值，生成不同sql語句，更新到資料庫 // db.SaveChanges(); //} //修改 //using (var db = new TestEFEntities()) //{ // Student u = new Student() {Id=5, Name = "kim", Sex = "1" }; // db.Entry(u).State = EntityState.Modified; // db.SaveChanges(); // Console.WriteLine("修改成功"); //} //修改 //using (var db = new TestEFEntities()) //{ // db.Database.Log = s => Debug.WriteLine(s); // var query = db.Students.FirstOrDefault(s => s.Id == 5); // if (query != null) // { // query.Name = "kim"; // query.Sex = "1"; // db.SaveChanges(); // } // db.SaveChanges(); // Console.WriteLine("修改成功"); //} //////分組 //using (var db = new TestEFEntities()) //{ // //.Select(m => m.Max(o => o.Id) // db.Database.Log = s => Debug.WriteLine(s); // //db.Database.Log = s => File.("a.txt",s); // //List <Student> list = new List<Student>(); // var temp1 = db.Students.GroupBy(x => x.Name).Select(s=>s.Key).ToList(); // // db.SaveChanges(); // Console.WriteLine(temp1); // Console.ReadKey(); //} //模糊查詢 //using (var db=new TestEFEntities()) //{ // db.Database.Log = s => Debug.WriteLine(s); // var query = db.Students.Where(s => s.Name.Contains("k")).ToList(); //} //排序 //using (var db = new TestEFEntities()) //{ // db.Database.Log = s => Debug.WriteLine(s); // //var query = db.Students.OrderBy(s => s.Name).OrderByDescending(s=>s.Id).ToList(); // var query = db.Students.OrderBy(s => s.Id).ToList(); //} // //using (var db = new TestEFEntities()) //{ // db.Database.Log = s => Debug.WriteLine(s); // var list2 =db.teachers.SelectMany(t => t.Student).Where(s => s < 60); //} //ForEach遍歷 //using (var db = new TestEFEntities()) //{ // db.Database.Log = s => Debug.WriteLine(s); // var _student = db.Students.ToList(); // // db.Students.ToList().ForEach(f => Console.WriteLine(f.Name)); // //_student.ForEach(s => { // // s.Name = "aaaa"; // // s.Score = 89; // //}); //} //Console.ReadKey(); //using (var db = new TestEFEntities()) //{ // db.Database.Log = s => Debug.WriteLine(s); // //返回多條符合結果的資料 // var st = db.Students.ToList().FindAll(s => s.Score >= 78);//find效能>where // var st1 = db.Students.Where(s => s.Score >= 78).ToList(); // //返回-條符合結果的資料 // var ff = db.Students.ToList().Find(s=>s.Score>78); // var ff2 = db.Students.FirstOrDefault(s => s.Score > 78); // //檢查後面條件是否成立，成立則返回true，否則返回false // var ee = db.Students.ToList().Exists(s=>s.Score==62); // Console.WriteLine(ee); //} //Console.ReadKey(); //刪除多條符合條件的一批資料 //using (var db = new TestEFEntities()) //{ // db.Database.Log = s => Debug.WriteLine(s); // //var n = new Student() { Id =( 1,2 )}; // //db.Students.Attach(n); // var usr = db.Students.ToList().FindAll(s => s.Score >= 78); // db.Students.RemoveRange(usr); // db.SaveChanges(); // Console.WriteLine(); //} //Console.ReadKey(); // //using (var db = new TestEFEntities()) //{ // db.Database.Log = s => Debug.WriteLine(s); // //var stu = db.Students.ToList().FindAll(s => s.Name == "k"); // var stu = db.Students.ToList().RemoveAll(s => s.Id == 5); // db.SaveChanges(); // Console.WriteLine(stu); //} #endregion List<Student> students = new List<Student>(); students.Add(new Student() { Name = "crank arm", Sex = "1", Score = 90 }); students.Add(new Student() { Name = "crank arm", Sex = "1", Score = 78 }); students.Add(new Student() { Name = "crank arm 80", Sex = "1", Score = 80 }); students.Add(new Student() { Name = "crank arm", Sex = "1", Score = 70 }); students.Add(new Student() { Name = "crank arm", Sex = "1", Score = 79 }); students.Add(new Student() { Name = "crank arm", Sex = "1", Score = 89 }); students.Add(new Student() { Name = "crank arm", Sex = "1", Score = 34 }); students.Add(new Student() { Name = "crank arm12312", Sex = "1", Score = 78 }); students.Add(new Student() { Name = "crank arm", Sex = "1", Score = 56 }); students.Add(new Student() { Name = "crank arm23432432", Sex = "1", Score = 78 }); students.Add(new Student() { Name = "crank arm", Sex = "1", Score = 40 }); #region MyRegion //返回第一個符合條件的陣列成員所在的位置 // var index = students.FindIndex(s => s.Score == 78); //返回符合條件的陣列成員最後一個元素 //var index = students.FindLast(s=>s.Score==78); //返回符合所定義的條件中成員最後一個匹配的項從零開始的索引 //var index = students.FindLastIndex(s=>s.Score==90); //查詢字串首次出現的位置，返回索引值 //string test = "az fy"; //Console.WriteLine(test.IndexOf("z")); //Insert在list裡面插入一個實體，資料的位置由自己指定 //students.Insert(10,new Student { Id=1,Name= "crank arm",Sex="1",Score=100 }); //foreach (var item in students) //{ // Console.WriteLine(item.Id.ToString()+" "+item.Name + " " + item.Sex + " " + item.Score); //} //對要查詢的字串從後往前查詢，找到第一個匹配的位置 //string test = "abcdefjjkk"; //Console.WriteLine(test.LastIndexOf("j")); //ToArray的使用是將一個集合轉成一個數組返回集合裡包含的所有元素 //Student[] stu = students.ToArray(); //Console.WriteLine(stu[9].Name); //陣列轉集合 // int[] alist = new int[] { 23, 24, 29 }; //List<int> sd = alist.ToList(); // foreach (var item in sd) // { // Console.WriteLine(item); // } #endregion #region MyRegion //foreach (var item in students) //{ // Console.WriteLine(item.Name + " "); //} //Console.WriteLine("----------------------------"); //修改 //students.ForEach(f => // { // if (f.Score == 80) // { // f.Name = "則是一個"; // f.Sex = "2"; // f.Score = 99; // } // }); //foreach (var item in students) //{ // Console.WriteLine(item.Name+" "); //} //Console.WriteLine(students); //Console.ReadKey(); //RemoveAll刪除 //students.RemoveAll(f=>f.Score==40); //Remove刪除 //var delete = students.Find(s => s.Score == 56); //students.Remove(delete); //模糊查詢 // var stu= students.Where(s=>s.Name.Contains("80")); //OrderBy升序，OrderByDescending降序 //var stu = students.OrderBy(s => s.Score).OrderByDescending(s=>s.Name).ToList(); // First //var stu = students.First(s => s.Score == 80); //Console.WriteLine(stu.Score); // FirstOrDefault //var stu = students.Select(s => s.Score == 90).FirstOrDefault(); //Console.WriteLine(stu); #endregion //分組 //var stu=students.GroupBy(s=>s.Score).ToList(); //foreach (var item in stu) //{ // Console.WriteLine(item.Key); //} var ss = students.FindIndex(f => f.Score == 80); var sss = students.FindLast(f => f.Score == 80); var sd = students.FindLastIndex(f => f.Score == 80); Console.WriteLine(sd); foreach (var item in students) { Console.WriteLine(item); } Console.WriteLine("--------------------------------"); Student[] st = students.ToArray(); Console.WriteLine(st[0].Score); //RemoveRange時刪除指定某一段索引的值 //RemoveAt是刪除指定索引的值 // students.RemoveRange(1,3); //var st = students.ToList().FindAll(s => s.Score > 70); //students.RemoveAt(1); //RemoveAll是刪除指定資料值 //var st = students.RemoveAll(s => s.Score == 90); //foreach (var item in students) //{ // Console.WriteLine(item.Score); //} List<Student> m_students = new List<Student>(); m_students.Add(new Student() { Name = "crank arm", Sex = "1", Score = 1 }); m_students.Add(new Student() { Name = "crank arm", Sex = "1", Score = 1 }); m_students.Add(new Student() { Name = "crank arm 80", Sex = "1", Score = 1 }); m_students.Add(new Student() { Name = "crank arm", Sex = "1", Score = 1 }); m_students.Add(new Student() { Name = "crank arm", Sex = "1", Score = 1 }); m_students.Add(new Student() { Name = "crank arm", Sex = "1", Score = 89 }); m_students.Add(new Student() { Name = "crank arm", Sex = "1", Score = 34 }); m_students.Add(new Student() { Name = "crank arm12312", Sex = "1", Score = 78 }); m_students.Add(new Student() { Name = "crank arm", Sex = "1", Score = 56 }); m_students.Add(new Student() { Name = "crank arm23432432", Sex = "1", Score = 78 }); m_students.Add(new Student() { Name = "crank arm", Sex = "1", Score = 40 }); //AddRange是新增到陣列的末尾 //students.AddRange(m_students); //Where是按指定條件查詢，返回結果集，必須要加條件 //select是按指定的條件查詢，返回Bool型別 //var s = students.Where(f => f.Name.Contains("80")).ToList(); //var ss = students.Select(f => f.Name.Contains("32")).ToList(); //Insert是指把新增插入到指定的序列 // students.Insert(7, new Student { Name = "111111111111111111111", Sex = "3", Score = 100 }); //foreach (var item in students) //{ // Console.WriteLine(item.Name + " " + item.Sex + " " + item.Score); //} Console.ReadKey(); }