Entity Framework - Linq To Entity use

1. Projection

Code
using(var ctx=new SchoolEntities())
{
    ObjectQuery<Courses> courses = ctx.Courses;
    IQueryable<Courses> allcourses = from c in courses
                                     select c;
    Console.WriteLine(courses.ToTraceString());
}

2. Where

Code
using(var ctx=new SchoolEntities())
{
    ObjectQuery<Courses> courses = ctx.Courses;
    IQueryable<Courses> allcourses = from c in courses
                                     where c.CourseName == "Act"
                                     select c;
}

3.Pagination

Code
using(var ctx=new SchoolEntities())
{
    ObjectQuery<Courses> courses = ctx.Courses;
    IQueryable<Courses> allcourses = from c in courses
                                     orderby c.CourseType
                                     select c.Skip(0).Take(100);
}

4. Aggregation (Average, Max, Min, Count, Sum)

using (var ctx = new  SchoolEntities())
{
    var older  =  ctx.Persons.Max(p => p.Age);
    Console.WriteLine(older.Value);
}

5. Join

using (var ctx = new  SchoolEntities())
{
    var query  =  from c  in  ctx.Courses
                join d  in  ctx.CourseDetails
                on d.CourseID equals c.CourseID
                select  new {
                    c, d.Info};
}

Reproduced in: https: //www.cnblogs.com/crossingdawn/archive/2009/07/27/1532212.html