//创建EF上下文
  Model.ModelContainer db = new Model.ModelContainer();  //下面有线程内实例唯一的例子
  UserInfo info = new UserInfo();
  info.Name = "张三";
  db.UserInfo.Add(info); //添加数据
  db.SaveChanges(); //最后必须SaveChanges()才能保存，把状态的实体映射回数据库。
  //info.Id = 1; //修改或删除操作，必须要有主键。
  //db.Entry<T>(entity).State = EntityState.Added;  //添加
  //db.Entry<T>(entity).State = EntityState.Modified;  //修改
  //db.Entry<T>(entity).State = EntityState.Deleted;  //删除

public T AddEntity(T entity) 
{
    //EF4.0的写法  
    添加实体
    //db.CreateObjectSet<T>().AddObject(entity);
    //EF5.0的写法
    db.Entry<T>(entity).State = EntityState.Added;
    //下面的写法统一
    db.SaveChanges();
    return entity;
}
public bool UpdateEntity(T entity)
{
    //EF4.0的写法
    //db.CreateObjectSet<T>().Addach(entity);
    //db.ObjectStateManager.ChangeObjectState(entity, EntityState.Modified);
    //EF5.0的写法 
   db.Set<T>().Attach(entity); 
   db.Entry<T>(entity).State = EntityState.Modified; 
   return db.SaveChanges() > 0; 
}
public bool DeleteEntity(T entity)
{
    //EF4.0的写法 
   //db.CreateObjectSet<T>().Addach(entity);
   //db.ObjectStateManager.ChangeObjectState(entity, EntityState.Deleted);
   //EF5.0的写法
   db.Set<T>().Attach(entity);
   db.Entry<T>(entity).State = EntityState.Deleted;
   return db.SaveChanges() > 0;
}

public IQueryable<T> LoadEntities(Func<T, bool> whereLambda)
{
    //EF4.0的写法
    //return db.CreateObjectSet<T>().Where<T>(whereLambda).AsQueryable();
    //EF5.0的写法
    return db.Set<T>().Where<T>(whereLambda).AsQueryable();
}
执行SQL语句
//EF4.0的写法
public int ExcuteSql(string sql, params ObjectParameter[] parameters)
{
    return DbContext.ExecuteFunction(sql, parameters);
}
//EF5.0的写法
public int ExecuteSql(string sql, params System.Data.SqlClient.SqlParameter[] pars)
{
     return DbContext.Database.ExecuteSqlCommand(sql, pars);
}

public class BaseRepository<T> where T:class,new ()
    {
        private DbContext DbContext
        {
            get
            {
                return DbContextFactory.CreateDbContext(); //创建唯一实例。
            }
        }
        //简单查询
        public IQueryable<T> LoadEntities(Expression<Func<T, bool>> whereLambda)
        {
            return DbContext.Set<T>().Where(whereLambda).AsQueryable();
        }
        //分页查询 ***
        public IQueryable<T> LoadPageEntities<S>(int pageSize, int pageIndex, out int totalCount, Expression<Func<T, bool>> whereLambda, bool isAsc, Expression<Func<T, S>> orderBy)
        {
            IQueryable<T> result = DbContext.Set<T>().Where(whereLambda).AsQueryable();
            totalCount = result.Count();  //返回总记录条数
            if (isAsc)
            {
                result = result.OrderBy(orderBy)
                    .Skip(pageSize * (pageIndex - 1))
                    .Take(pageSize)
                    .AsQueryable();
            }
            else
            {
                result = result.OrderByDescending(orderBy)
                    .Skip(pageSize * (pageIndex - 1))
                    .Take(pageSize)
                    .AsQueryable();
            }
            return result;
        }

        public T Add(T entity)
        {
            DbContext.Set<T>().Add(entity);
            return entity;
        }

        public bool Detele(T entity)
        {
            DbContext.Entry(entity).State = EntityState.Deleted;
            return true;
        }

        public bool Update(T entity)
        {
            DbContext.Entry(entity).State = EntityState.Modified;
            return true;
        }
    }

    /// <summary>
    /// 保证EF的上下文。线程内实例唯一，一次请求一个实例、
    /// </summary>
    public static class DbContextFactory
    {
        public static DbContext CreateDbContext()
        {
            //线程内实例唯一
            DbContext db = (DbContext)HttpContext.Current.Items["DbContext"];
            if (db == null)
            {
                db = new Model.ModelContainer();
                HttpContext.Current.Items.Add("DbContext", db);
            }
            return db;
        }
    }