you can use SqlDataReader, sample code
using (SqlConnection connection = new SqlConnection(connectionString))
{
connection.Open();
using (SqlCommand command = new SqlCommand("SELECT top 1 Item_factor, SUM(number_item_factor) AS EX1 FROM Detail_factor_sell GROUP BY Item_factor", connection))
{
SqlDataReader reader = command.ExecuteReader();
if (reader.Read())
{
string Item_factor= reader.GetString(0);
int sumNumber_item_factor= reader.GetInt32(1);
}
}
}