Hi Praveen,

I am slightly confused with meaning of "Joined'. Is it means, you are looking to concatenate the rows or you want to perform Database Join type.

If you are looking for database join, I suggest to use Linq Join method.

If you are looking to merge the both result sets, You can use AddRange() method of List. Get the database records into a generic list and add it to your collection

     oExistingCollection.AddRange(oNewData);

Did you take a look at the Web Services data source option with SSRS? This allows you to run a report based on the data provided by a Web Service.

Within your Web Service, you can write the code to join your in-memory data with the data in the database. This can be done either by passing the info to the database as an XML parameter (where you do the join in the database) or doing it in the application by manipulating the data table returned by the stored procedure/DB code.