Loading multiple tables in a datagrid

DataRelation relTest;                                            
relTest = new DataRelation("DataSetRel",dset.Tables["Table1"].Columns["table1_Id"],dsset.Tables["table2"].Columns["table2_id"]);
dset.Relations.Add(relTest);

assign this dset to datasource of grid.

http://social.msdn.microsoft.com/Forums/en-US/adodotnetdataproviders/thread/f122d7f4-3b7d-4d93-bd0f-8bb57cd990a4

Other option if you use framework 3.5 or above then use LINQ-Dataset

please refer

http://msdn.microsoft.com/en-us/library/bb386977.aspx

http://msdn.microsoft.com/en-us/library/bb386969.aspx

var query =
    from order in orders.AsEnumerable()
    join detail in details.AsEnumerable()
    on order.Field("SalesOrderID") equals
        detail.Field("SalesOrderID")
    where order.Field("OnlineOrderFlag") == true
    && order.Field("OrderDate").Month == 8
    select new
    {
        SalesOrderID =
            order.Field("SalesOrderID"),
        SalesOrderDetailID =
            detail.Field("SalesOrderDetailID"),
        OrderDate =
            order.Field("OrderDate"),
        ProductID =
            detail.Field("ProductID")
    };

hope this will help u.