public ActionResult DeleteConfirmed(int id)
        {
            Semester semester = db.Semesters.Single(s => s.SemesterID == id);

            db.Semesters.DeleteObject(semester);
            db.SaveChanges();
            return(RedirectToAction("Index"));
        }
        public ActionResult ImportExcel(HttpPostedFileBase file)
        {
            int clsCount = 0;
            int stuCount = 0;

            if (Request.Files["FileUpload"].ContentLength > 0)
            {
                string fileExtension =
                    System.IO.Path.GetExtension(Request.Files["FileUpload"].FileName);

                if (fileExtension == ".xls" || fileExtension == ".xlsx")
                {
                    // Create a folder in App_Data named ExcelFiles because you need to save the file temporarily location and getting data from there.
                    string fileLocation = string.Format("{0}/{1}", Server.MapPath("~/Content/Temp"),
                                                        Request.Files["FileUpload"].FileName);

                    if (System.IO.File.Exists(fileLocation))
                    {
                        System.IO.File.Delete(fileLocation);
                    }

                    Request.Files["FileUpload"].SaveAs(fileLocation);
                    string excelConnectionString = string.Empty;

                    excelConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + fileLocation + ";Extended Properties=\"Excel 12.0;HDR=Yes;IMEX=2\"";
                    //connection String for xls file format.
                    if (fileExtension == ".xls")
                    {
                        excelConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + fileLocation + ";Extended Properties=\"Excel 8.0;HDR=Yes;IMEX=2\"";
                    }
                    //connection String for xlsx file format.
                    else if (fileExtension == ".xlsx")
                    {
                        excelConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + fileLocation + ";Extended Properties=\"Excel 12.0;HDR=Yes;IMEX=2\"";
                    }



                    //Create Connection to Excel work book and add oledb namespace
                    OleDbConnection excelConnection = new OleDbConnection(excelConnectionString);
                    excelConnection.Open();
                    DataTable dt = new DataTable();

                    dt = excelConnection.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
                    if (dt == null)
                    {
                        return(null);
                    }

                    String[] excelSheets = new String[dt.Rows.Count];
                    int      t           = 0;
                    //excel data saves in temp file here.
                    foreach (DataRow row in dt.Rows)
                    {
                        excelSheets[t] = row["TABLE_NAME"].ToString();
                        t++;
                    }
                    OleDbConnection excelConnection1 = new OleDbConnection(excelConnectionString);
                    DataSet         ds = new DataSet();

                    string query = string.Format("Select * from [{0}]", excelSheets[0]);
                    using (OleDbDataAdapter dataAdapter = new OleDbDataAdapter(query, excelConnection1))
                    {
                        dataAdapter.Fill(ds);
                    }
                    Class   dbclass;
                    Student dbStudent;
                    String  tmp;
                    int     majorID;
                    int     classID;
                    String  value;
                    // insert tung dong cua file
                    for (int i = 0; i < ds.Tables[0].Rows.Count; i++)
                    {
                        //insert class
                        dbclass = new Class();
                        //lay gia tri majorid dua tren majorshorname
                        tmp     = ds.Tables[0].Rows[i]["Major"].ToString();
                        majorID = _db.Majors.SingleOrDefault(m => m.ShortName == tmp).MajorID;
                        //check class da duoc ton tai trong database
                        dbclass.MajorID   = majorID;
                        dbclass.ClassName = ds.Tables[0].Rows[i]["Class Name"].ToString();
                        value             = dbclass.ClassName;
                        dbclass.IsActive  = true;
                        bool isExist = _db.Classes.AsEnumerable().Any(row => row.ClassName == value);
                        if (isExist == false)
                        {
                            _db.Classes.AddObject(dbclass);
                            _db.SaveChanges();
                            clsCount++;
                        }
                        //insert student

                        tmp                   = ds.Tables[0].Rows[i]["Class Name"].ToString();
                        classID               = _db.Classes.SingleOrDefault(c => c.ClassName == tmp).ClassID;
                        dbStudent             = new Student();
                        dbStudent.ClassID     = classID;
                        dbStudent.FullName    = ds.Tables[0].Rows[i]["Student Name"].ToString();
                        dbStudent.StudentCode = ds.Tables[0].Rows[i]["Student Code"].ToString();
                        dbStudent.Birthdate   = DateTime.Parse(ds.Tables[0].Rows[i]["Birthdate"].ToString());
                        dbStudent.CitizenID   = ds.Tables[0].Rows[i]["CitizenID"].ToString();
                        dbStudent.IsActive    = true;
                        value                 = dbStudent.StudentCode;
                        bool test = _db.Students.AsEnumerable().Any(d => d.StudentCode == value);
                        if (test == false)
                        {
                            _db.Students.AddObject(dbStudent);
                            _db.SaveChanges();
                            stuCount++;
                        }
                    }

                    ds.Dispose();
                    excelConnection.Close();
                }

                else
                {
                }
            }
            return(RedirectToAction("Import", new { numCls = clsCount, numStu = stuCount }));
        }