private static void AddUpdateDeleteEntityDisConnectedMode()
{
Console.WriteLine("Adding a new student in disconnected mode started");
var newStudent = new Student()
{
StudentName = "new good student"
};
var existingStudent = new Student()
{
StudentID = 64, StudentName = "is update by me"
};
//Keep in mind if any exception happens during the transaction
//all the transacation will be rollbacked and cancelled
using (var context = new mySchooldbEntities())
{
context.Database.Log = Console.WriteLine;
context.Entry(existingStudent).State = existingStudent.StudentID == 0 ?
System.Data.Entity.EntityState.Added : System.Data.Entity.EntityState.Modified;
context.Entry(newStudent).State = newStudent.StudentID == 0 ?
System.Data.Entity.EntityState.Added : System.Data.Entity.EntityState.Modified;
context.SaveChanges();
}
Console.WriteLine("Adding a new student disconnected mode is finished");
}
private static void LinqToEntitiesQuery()
{
Console.WriteLine("LinqToEntitits Query starts");
using (var context = new mySchooldbEntities())
{
context.Database.Log = Console.WriteLine;
//Retrive by Query Syntax
var students = from s in context.Students
where s.StudentName == "Donald"
select s;
foreach (var student in students)
{
Console.WriteLine(student.StudentName);
}
Console.WriteLine("students with the same name");
var studentsWithSameName = context.Students
.GroupBy(s => s.StudentName) // groups them by name
.Where(g => g.Count() > 1) // gives the groups that has more than 1 record
.Select(g => g.Key); // gives me the key for grouping the objects
foreach (var student in studentsWithSameName)
{
Console.WriteLine(student);
}
}
}
public static void AddUpdateDeleteEntityConnectedMode()
{
Console.WriteLine("Adding a new student in connected mode started");
using (var context = new mySchooldbEntities())
{
context.Database.Log = Console.WriteLine;
//for insertion you need to add the entity into the list of
//objects and then save it
var newStudent = context.Students.Add(new Student()
{
StudentName = "Reza4",
StudentAddress = new StudentAddress()
{
Address1 = "address 12",
City = "Montreal"
},
Height = decimal.Parse("2.5")
});
context.SaveChanges();
//for update you need to take the object and then modify it
//and then save it back again
newStudent.StudentName = "update name";
context.SaveChanges();
context.Students.Remove(newStudent);
context.SaveChanges();
}
}
private static void ExcuteRawSQLQueries()
{
Console.WriteLine("RawSQLQueries started");
using (var context = new mySchooldbEntities())
{
context.Database.Log = Console.WriteLine;
var studentList = context.Students.SqlQuery("select * from Students").ToList();
}
}
private static void FindEntity()
{
Console.WriteLine("find an entity started");
using (var context = new mySchooldbEntities())
{
context.Database.Log = Console.WriteLine;
var student = context.Students.Find(69);
Console.WriteLine($"{student.StudentName}");
}
}
