// 将创建的data实体添加到ObjectContext
db.Data.Attach(data);
// 手动设置状态为修改 
db.ObjectStateManager.ChangeObjectState(data, EntityState.Modified);
db.SaveChanges();

@Html.Action("left","system") // 目录为system/left/ 的action

var singleResult = db.ExecuteStoreQuery<string>("select count(*) as counts from userinfo");
foreach (var item in singleResult)
{ // 只有一条信息
    string result = item;
}