public int UpData(T model, params string[] proNames)        {                          //4.1将 对象 添加到 EF中                 DbEntityEntry entry = null;                var set = db.Set
     
      ().Find(DbContextExtensions.GetEntityKey(db, model));                if (set != null)                {                                      db.Entry
      
       (set).State = EntityState.Detached;                }                                 entry = db.Entry
       
        (model);                                //4.2先设置 对象的包装 状态为 Unchanged                            entry.State = EntityState.Unchanged;                //4.3循环 被修改的属性名 数组                foreach (string proName in proNames)                {                    //4.4将每个 被修改的属性的状态 设置为已修改状态;后面生成update语句时，就只为已修改的属性 更新                    entry.Property(proName).IsModified = true;                }                                 return  db.SaveChanges();                                   }
       
      
     

　　

public static class DbContextExtensions    {        public static int GetEntityKey(this DbContext context, object entity)        {            try            {                string name = entity.GetType().ToString().Replace("Model.","");                              var adapter = context as IObjectContextAdapter;                EntityKey enkey = adapter.ObjectContext.CreateEntityKey(name, entity);                string id = enkey.EntityKeyValues[0].Value.ToString();                return int.Parse(id);            }            catch            {                return 0;            }        }    }