public void AddStudent(string firstName, string LastName)
{
var student = new Student()
{
StudentId = 1, FirstName = firstName, LastName = LastName
};
student.Enrollments = new List <Enrollment>()
{
new Enrollment()
{
CourseCourseId = 1
},
new Enrollment()
{
CourseCourseId = 2
},
new Enrollment()
{
CourseCourseId = 3
},
new Enrollment()
{
CourseCourseId = 4
}
};
using (var dbcontext = new ModelFirstContainer())
{
dbcontext.Students.Add(student);
dbcontext.SaveChanges();
}
}
public void AddCourse(string name, string credits)
{
var course = new Course()
{
CourseId = 1, Name = name, Credits = credits
};
using (var dbcontext = new ModelFirstContainer())
{
dbcontext.Courses.Add(course);
dbcontext.SaveChanges();
}
}
static void Main(string[] args)
{
using (var context = new ModelFirstContainer())
{
var student = context.Students.Where(w => w.Name == "Mark").FirstOrDefault();
var courseList = context.Courses.Where(w => w.Name != "Mech").ToList();
//Query Syntax
var studentsEnrolled = (from s in context.Students join e in context.Enrollments on s.StudentId equals e.StudentStudentId select s.Name).Distinct().ToList();
//Method syntax
var studentsEnrolled1 = context.Students.Join(context.Enrollments, s => s.StudentId, e => e.StudentStudentId, (s, e) => new { s.Name }).Distinct().ToList();
//Left Join
/*
* Select S.Name, COUNT(E.EnrollmentId) from Students S
* LEFT JOIN Enrollments E ON S.StudentId=E.StudentStudentId
* GROUP BY S.Name
*/
var LeftJoin = (from s in context.Students
join e in context.Enrollments
on s.StudentId equals e.StudentStudentId
group s by s.Name
into es from e1 in es.DefaultIfEmpty()
select new { es.Key, count = es.Count() }).Distinct().ToList();
foreach (var student1 in LeftJoin)
{
Console.WriteLine("{0}-{1}", student1.Key, student1.count);
}
/*
* foreach(var course in courseList)
* {
* var enroll = new Enrollment()
* {
* Student = student,
* Course = course
* };
* context.Enrollments.Add(enroll);
* context.SaveChanges();
*
* }
*/
}
//
Console.ReadKey();
}
public Student GetStudent(int StudentId)
{
using (var dbcontext = new ModelFirstContainer())
{
dbcontext.Configuration.LazyLoadingEnabled = false;
//Eager loading
//var student = dbcontext.Students.Include("Enrollments").Where(w => w.StudentId == StudentId).FirstOrDefault();
//var student = dbcontext.Students.Where(w => w.StudentId == StudentId).FirstOrDefault();
var student = (from stud in dbcontext.Students where stud.StudentId == StudentId select stud).FirstOrDefault();
//Explicit Loading
dbcontext.Entry(student).Collection(s => s.Enrollments).Load();
return(student);
}
}
static void Main(string[] args)
{
using (var db = new ModelFirstContainer()) {
Department d = new Department();
d.DepartmentNo = 121;
d.Name = "Rajeev";
Worker w = new Worker();
w.WorkerID = 123;
w.Name = "John";
w.Place = "Jaipur";
HashSet <Worker> s = new HashSet <Worker>();
s.Add(w);
d.Workers = s;
db.Departments.Add(d);
try {
db.SaveChanges();
Console.WriteLine("The records are added..!!!!!");
Console.ReadKey();
}
catch (Exception e) {
}
}
}
