here's a clue...
SqlDataReader reader = cmd.ExecuteReader();
List<string> selected = new List<string>();
while (reader.Read())
{
selected.Add(reader["subcategory_id"].ToString());
}
listView1.SelectedItems.Clear();
for(int i=0;i<selected.count();i++)>
listView1.Items[(int)i].Selected = true;
</string></string>