Entity Framework - how to join tables without LINQ and with only string? - sql

Question

I have a question about Entity Framework. Please answer if you know answer on this. I have such query :
String queryRaw =
"SELECT " +
"p.ProductName AS ProductName " +
"FROM ProductEntities.Products AS p " +
"INNER JOIN CategoryEntities.Categories AS c " +
"ON p.CategoryID = c.CategoryID ";
ObjectQuery<DbDataRecord> query = new ObjectQuery<DbDataRecord>(queryRaw, entityContext);
GridView1.DataSource = query;
GridView1.DataBind();
Particularly I want to join few tables in one query, but I can NOT use LINQ and can NOT use ObjectQuery with objects mapped to DB fields inside my query. Because each entity creates dynamically. So this is what i can NOT use :
msdn.microsoft.com/en-us/library/bb425822.aspx#linqtosql_topic12
msdn.microsoft.com/en-us/library/bb896339%28v=VS.90%29.aspx
The question is can I use something like this instead of using objects?
query.Join ("INNER JOIN CategoryEntities.Category ON p.CategoryID = c.CategoryID ");
The purpose is to use Join method of ObjectQuery with syntax as in Where method :
msdn.microsoft.com/en-us/library/bb338811%28v=VS.90%29.aspx
Thanks, Artem

Answer 1

Any decision i see right now is to temporary convert ObjectQuery to string, add joined table as string and then convert it back to ObjectQuery :
RoutesEntities routesModel = new RoutesEntities(entityConnection);
String queryRaw = "SELECT " +
"rs.RouteID AS RouteID, " +
"rs.LocaleID AS LocaleID, " +
"rs.IsSystem AS IsSystem " +
"FROM RoutesEntities.Routes AS rs ";
_queryData = new ObjectQuery<DbDataRecord>(queryRaw, routesModel);
var queryJoin = _queryData.CommandText + " INNER JOIN LocalesEntities.Locales AS ls ON ls.LocaleID = rs.LocaleID ";
_queryData = new ObjectQuery<DbDataRecord>(queryJoin, routesModel);
Maybe someone has more consistent suggestions?

Answer 2

Finally I Found a better solution for this, we can use Sub Query inside main Query. For example :
var db = CustomEntity();
ObjectQuery<Categories> query1 = db.Categories.Where("it.CategoryName='Demo'").Select ("it.CategoryID");
var categorySQL = query1.ToTraceString().Replace("dbo", "CustomEntity"); // E-SQL need this syntax
ObjectQuery<Products> query2 = db.Categories.Where("it.CategoryID = (" + categorySQL + ")");
Some example is here :
http://msdn.microsoft.com/en-us/library/bb896238.aspx
Good luck!