Try lambda expression:
Datatable1.AsEnumerable().Where(s=>s.Field<stirng>("SomeColumn") == "SomeValue").CopyToDataTable(Datatable2, LoadOption.Upsert);
</stirng>
[Update]
Then how about this?
DataRow[] dr = DataTable1.Select("ColumnName='columnvalue'");
and then:
foreach (DataRow row in dr ) {
DataTable2.ImportRow(row);
}
--Amy