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How to query Entities in Entity Framework 4

开发者 https://www.devze.com 2022-12-30 09:23 出处:网络
In VS2008, I think it is EF1.0, this works just fine. string queryString = @\"SELECT VALUE USERS FROM ProjectDBEntities.Users AS User

In VS2008, I think it is EF1.0, this works just fine.

string queryString = @"SELECT VALUE USERS FROM ProjectDBEntities.Users AS User 
            INNER JOIN ProjectDBEntities.Favorites AS F ON F.FavUserId = User.UserId
            WHERE F.UserId = " + 3 + " ORDER BY F.Creat开发者_如何学运维eDate DESC ";

        System.Data.Objects.ObjectQuery<User> usersQuery =
                new System.Data.Objects.ObjectQuery<User>(queryString, context).Include("Detail");

        //int count = usersQuery.Count();
        foreach (User result in usersQuery)
            Console.WriteLine("User Name: {0}", result.UserName);

Same code in VS2010 EF4 it crashes on the foreach loop with the following error:

The result type of the query is neither an EntityType nor a CollectionType with an entity element type. An Include path can only be specified for a query with one of these result types.


var q = from u in ProjectDBEntities.Users
        from f in u.Favorites
        where f.User.Id == 3
        orderby f.CreateDate desc;

I'm making some presumptions about your entity model/property names since you don't show it, but this should give you the general idea.

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