How to solve the connection problem in the datagridview c#

Question

 

Hi friends

I find this error

 

 

 

in this code but I do not know is what I will add con.open () and con .close () to the code

 

 

Program.cmd.CommandText = "select utilisateur.User_name,site.Libelle_site,profil.Libelle_profil from utilisateur,site,profil,autorisation where utilisateur.Id_user=autorisation.Id_user and site.Id_site=autorisation.Id_site and profil.Id_profil=autorisation.Id_profil";

Program.dr = Program.cmd.ExecuteReader();

DataTable dt = new DataTable();

dt.Load(Program.dr);

dataGridView1.DataSource = dt;

dataGridView1.Refresh();