[渣译文] 使用 MVC 5 的 EF6 Code First 入门 系列：为ASP.NET MVC应用程序使用高级功能

        public async Task<ActionResult> Details(int? id)
        {
            if (id == null)
            {
                return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
            }
            //Department department = await db.Departments.FindAsync(id);
            string query = "select * from department where departmentid = @p0";
            Department department = await db.Departments.SqlQuery(query, id).SingleOrDefaultAsync();

            if (department == null)
            {
                return HttpNotFound();
            }
            return View(department);
        }

            var data = from student in db.Students
                       group student by student.EnrollmentDate into dateGroup
                       select new EnrollmentDateGroup()
                       {
                           EnrollmentDate = dateGroup.Key,
                           StudentCount = dateGroup.Count()
                       };

        public ActionResult About()
        {
            //var data = from student in db.Students
            //           group student by student.EnrollmentDate into dateGroup
            //           select new EnrollmentDateGroup()
            //           {
            //               EnrollmentDate = dateGroup.Key,
            //               StudentCount = dateGroup.Count()
            //           };
            string query = "select EnrollmentDate,count(*) as studentCount "
                + "From Person "
                + "where discriminator = ‘Student‘ "
                + "group by EnrollmentDate ";
            var data = db.Database.SqlQuery<EnrollmentDateGroup>(query);
            return View(data.ToList());
        }

        public ActionResult UpdateCourseCredits()
        {
            return View();
        }

        [HttpPost]
        public ActionResult UpdateCourseCredits(int ? multiplier)
        {
            if (multiplier != null)
            {
                ViewBag.RowsAffected = db.Database.ExecuteSqlCommand("update course Set Credits = Credits * {0}", multiplier);
            }
            return View();
        }

@model ContosoUniversity.Models.Course
@{
    ViewBag.Title = "UpdateCourseCredits";
}

<h2>UpdateCourseCredits</h2>

@if (ViewBag.RowsAffected == null)
{
    using (Html.BeginForm())
    {
        <p>
            Enter a number to multiply every course‘s credits by: @Html.TextBox("multiplier")
        </p>
        <p><input type="su" name="name" value="Update" /></p>
    }
}
@if (ViewBag.RowsAffected != null)
{
    <p>
        Number of rows updated: @ViewBag.RowsAffected
    </p>
}
<div>
    @Html.ActionLink("Back to List", "Index")
</div>

        private void ValidateOneAdministratorAssignmentPerInstructor(Department department)
        {
            if (department.InstructorID != null)
            {
                Department duplicateDepartment = db.Departments
                    .Include("Administrator")
                    .Where(d => d.InstructorID == department.InstructorID)
                    .FirstOrDefault();
                if (duplicateDepartment != null && duplicateDepartment.DepartmentID != department.DepartmentID)
                {
                    string errorMessage = string.Format(
                        "教师{0} {1}已经是{2}系的主任。",
                        duplicateDepartment.Administrator.FirstMidName,
                        duplicateDepartment.Administrator.LastName,
                        duplicateDepartment.Name);
                    ModelState.AddModelError(string.Empty, errorMessage);
                }
            }
        }

        [HttpPost]
        [ValidateAntiForgeryToken]
        public async Task<ActionResult> Edit([Bind(Include = "DepartmentID,Name,Budget,StartDate,RowVersion,InstructorID")] Department department)
        {
            try
            {
                if (ModelState.IsValid)
                {
                    ValidateOneAdministratorAssignmentPerInstructor(department);
                }
                if (ModelState.IsValid)
                {
                    db.Entry(department).State = EntityState.Modified;
                    await db.SaveChangesAsync();
                    return RedirectToAction("Index");
                }
            }
            catch (DbUpdateConcurrencyException ex)
            {
                var entry = ex.Entries.Single();
                var clientValues = (Department)entry.Entity;
                var databaseEntry = entry.GetDatabaseValues();
                if (databaseEntry == null)
                {
                    ModelState.AddModelError(string.Empty, "无法保存更改，系已经被其他用户删除。");
                }
                else
                {
                    var databaseValues = (Department)databaseEntry.ToObject();
                    if (databaseValues.Name != clientValues.Name)
                        ModelState.AddModelError("Name", "当前值: "
                            + databaseValues.Name);
                    if (databaseValues.Budget != clientValues.Budget)
                        ModelState.AddModelError("Budget", "当前值: "
                            + String.Format("{0:c}", databaseValues.Budget));
                    if (databaseValues.StartDate != clientValues.StartDate)
                        ModelState.AddModelError("StartDate", "当前值: "
                            + String.Format("{0:d}", databaseValues.StartDate));
                    if (databaseValues.InstructorID != clientValues.InstructorID)
                        ModelState.AddModelError("InstructorID", "当前值: "
                            + db.Instructors.Find(databaseValues.InstructorID).FullName);
                    ModelState.AddModelError(string.Empty, "当前记录已经被其他人更改。如果你仍然想要保存这些数据，"
                    + "重新点击保存按钮或者点击返回列表撤销本次操作。");
                    department.RowVersion = databaseValues.RowVersion;
                }
            }
            catch (RetryLimitExceededException)
            {
                ModelState.AddModelError(string.Empty, "无法保存更改，请重试或联系管理员。");
            }
            ViewBag.InstructorID = new SelectList(db.Instructors, "ID", "FullName", department.InstructorID);
            return View(department);
        }

                Department duplicateDepartment = db.Departments
                    .Include("Administrator")
                    .Where(d => d.InstructorID == department.InstructorID)
                    .AsNoTracking()
                    .FirstOrDefault();

        public ActionResult Index()
        {
            var courses = db.Courses;
            var sql = courses.ToString();
            return View(courses.ToList());
        }

        public ActionResult Index(int? SelectedDepartment)
        {
            var departments = db.Departments.OrderBy(q => q.Name).ToList();
            ViewBag.SelectedDepartment = new SelectList(departments, "DepartmentID", "Name", SelectedDepartment);
            int departmentID = SelectedDepartment.GetValueOrDefault();

            IQueryable<Course> courses = db.Courses
                .Where(c => !SelectedDepartment.HasValue || c.DepartmentID == departmentID)
                .OrderBy(d => d.CourseID)
                .Include(d => d.Department);
            var sql = courses.ToString();
            return View(courses.ToList());
        }

@using (Html.BeginForm())
{
    <p>选择系：@Html.DropDownList("SelectedDepartment", "All")</p>
    <input type="submit" name="name" value="筛选" />
}

SELECT 
    [Project1].[CourseID] AS [CourseID], 
    [Project1].[Title] AS [Title], 
    [Project1].[Credits] AS [Credits], 
    [Project1].[DepartmentID] AS [DepartmentID], 
    [Project1].[DepartmentID1] AS [DepartmentID1], 
    [Project1].[Name] AS [Name], 
    [Project1].[Budget] AS [Budget], 
    [Project1].[StartDate] AS [StartDate], 
    [Project1].[InstructorID] AS [InstructorID], 
    [Project1].[RowVersion] AS [RowVersion]
    FROM ( SELECT 
        [Extent1].[CourseID] AS [CourseID], 
        [Extent1].[Title] AS [Title], 
        [Extent1].[Credits] AS [Credits], 
        [Extent1].[DepartmentID] AS [DepartmentID], 
        [Extent2].[DepartmentID] AS [DepartmentID1], 
        [Extent2].[Name] AS [Name], 
        [Extent2].[Budget] AS [Budget], 
        [Extent2].[StartDate] AS [StartDate], 
        [Extent2].[InstructorID] AS [InstructorID], 
        [Extent2].[RowVersion] AS [RowVersion]
        FROM  [dbo].[Course] AS [Extent1]
        INNER JOIN [dbo].[Department] AS [Extent2] ON [Extent1].[DepartmentID] = [Extent2].[DepartmentID]
        WHERE @p__linq__0 IS NULL OR [Extent1].[DepartmentID] = @p__linq__1
    )  AS [Project1]
    ORDER BY [Project1].[CourseID] ASC