The problem now is that SQLDataReader doesn't return a dataset ... it merelt
reads etc.

I found this
ms-help://MS.VSCC/MS.MSDNVS/cpguide/html/cpcontheadonetdatareader.htm

While a DataReader is open, you can retrieve schema information about the
current result set using the GetSchemaTable method. GetSchemaTable returns a
DataTable object  populated with rows and columns that contain the schema
information for the current result set.


[C#]

DataTable schemaTable = myReader.GetSchemaTable();

foreach (DataRow myRow in schemaTable.Rows)
{
foreach (DataColumn myCol in schemaTable.Columns)
Console.WriteLine(myCol.ColumnName + " = " + myRow[myCol]);
Console.WriteLine();
}

So try

DataTable oReadDT = oReader.GetSchemaTable();