EF helper

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

namespace WEBAPI.Models
{
    public class EFHelper<T> where T : class, new()
    {
        SchoolDB db = new SchoolDB();
        public int Add(T t) 
        {
            db.Set<T>().Add(t);
            return db.SaveChanges();
        }

        public int Update(T t)
        {
            db.Set<T>().Attach(t);
            db.Entry<T>(t).State = System.Data.Entity.EntityState.Modified;
            return db.SaveChanges();
        }

        public int Delete(int Id)
        {
            T t = db.Set<T>().Find(Id);
            db.Set<T>().Remove(t);
            return db.SaveChanges();
        }

        public List<T> GetAll()
        {
            return db.Set<T>().ToList();
        }

        public T GetEntity(int Id)
        {
            return db.Set<T>().Find(Id);
        }
    }
}