How to filter and combine 2 datasets in C#

Question

I am building a web page to show a customer what software they purchased and to give them a link to download said software. Unfortunately, the data on what was purchased and the download information are in separate databases so I can't just take care of it with joins in an SQL query.

The common item is SKU. I'll be pulling a list of SKUs from the customer purchases database and on the download table is a comma delineated list of SKUs associated with that download. My intention, at the moment, is to create from this one datatable to populate a GridView.

Any suggestions on how to do this efficiently would be appreciated. If it helps, I can pretty easily pull back the data as a DataSet or a DataReader, if either one would be better for this purpose.

Answer 1

As long as the two databases are on the same physical server (assuming MSSQL) and the username/password being used in the connection string has rights to both DBs, then you should be able to perform a join across the two databases. Example:

select p.Date,
       p.Amount,
       d.SoftwareName,
       d.DownloadLink
from   PurchaseDB.dbo.Purchases as p
join   ProductDB.dbo.Products as d on d.sku = p.sku
where  p.UserID = 12345

Answer 2

Why not create a Domain object based approach to this problem:

public class CustomerDownloadInfo
{
    private string sku;
    private readonly ICustomer customer;

    public CustomerDownloadInfo(ICustomer Customer){
        customer = Customer;
    }

    public void AttachSku(string Sku){
        sku = Sku;
    }

    public string Sku{
        get { return sku; }
    }

    public string Link{
        get{    
            // etc... etc...          
        }
    }
}

There are a million variations on this, but once you aggregate this information, wouldn't it be easier to present?

Answer 3

I am thinking off the top of my head here. If you load both as Data Tables in the same Data Sets, and define a relation between the two over SKU, and then run a query on the Data Set which produces the desired result.