inner join on multiple tables in a DataSet - asp.net

Question

I have a data set which has 2 data tables.Both these tables are retrieved from 2 distinct Oracle Databases (physically and logically separate).
I need to do a Inner Join on these two tables which reside in 1 dataset. And then display the result in a gridview.
Are there any possibilities of doing SQL Joins on tables inside a Dataset?
If yes, does anyone have a worked out example? If not, can someone point me in the right direction - I do not wish to do any "hacks" (manually looping thru and other iterations of that sorts) as I believe there will be a way to do it within the environment, just need the right approach.
This is in VB .net so would appreciate a more relevant code BUT any help is highly appreciated.

Answer 1

Try this method helper:
private DataTable JoinDataTables(DataTable t1, DataTable t2, params Func<DataRow, DataRow, bool>[] joinOn)
{
DataTable result = new DataTable();
foreach (DataColumn col in t1.Columns)
{
if (result.Columns[col.ColumnName] == null)
result.Columns.Add(col.ColumnName, col.DataType);
}
foreach (DataColumn col in t2.Columns)
{
if (result.Columns[col.ColumnName] == null)
result.Columns.Add(col.ColumnName, col.DataType);
}
foreach (DataRow row1 in t1.Rows)
{
var joinRows = t2.AsEnumerable().Where(row2 =>
{
foreach (var parameter in joinOn)
{
if (!parameter(row1, row2)) return false;
}
return true;
});
foreach (DataRow fromRow in joinRows)
{
DataRow insertRow = result.NewRow();
foreach (DataColumn col1 in t1.Columns)
{
insertRow[col1.ColumnName] = row1[col1.ColumnName];
}
foreach (DataColumn col2 in t2.Columns)
{
insertRow[col2.ColumnName] = fromRow[col2.ColumnName];
}
result.Rows.Add(insertRow);
}
}
return result;
}