EF 直接修改数据，不再查询数据库

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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<T>().Find(DbContextExtensions.GetEntityKey(db, model));                  if (set != null)                {                                       db.Entry<T>(set).State = EntityState.Detached;                  }                                  entry = db.Entry<T>(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();                                     }

　　

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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;          }        }  }