var query = from p in ds.Tables["Id"].AsEnumerable()
where p.Field("ID") == "1" && p.Field("Name") == "test" select p;
if (query.Count() > 0)
{
dt = query.CopyToDataTable();
}
Read more: http://feeds.dzone.com/~r/dzone/snippets/~3/2ydBYwNuC1s/14495