C#

string sConnection = "Data Source=127.0.0.1,1433;Persist Security Info=True;Initial Catalog=GMAO;User ID=sa;Password=sa";
   string sSQL = "SELECT com FROM energie; ";
   SqlConnection conn = new SqlConnection(sConnection);
   SqlCommand comm = new SqlCommand(sSQL, conn);
   DataSet ds = new DataSet();
   SqlCeDataAdapter da = new SqlCeDataAdapter();
   SqlDataReader dr = null;
   try
   {
    
    comm.Connection.Open();
    da.Fill(ds, "SQL Temp Table");
    foreach(DataRow d in ds.Tables[0].Rows)
    comboBox1.Items.Add(d.ToString());
   }
   catch (SqlException ex)
   {
    //MessageBox.Show("connexion impossible");
    MessageBox.Show(ex.Message);
    return;
   }

   dr.Close();
   comm.Connection.Close();
  }

string sConnection = "Data Source=127.0.0.1,1433;Persist Security Info=True;Initial Catalog=GMAO;User ID=sa;Password=sa";
string sSQL = "SELECT ID, com FROM energie";

SqlConnection conn = new SqlConnection(sConnection);
SqlCommand comm = new SqlCommand(sSQL, conn);
SqlDataAdapter da = new SqlDataAdapter(comm);

try
{
    DataSet ds = new DataSet();

    comm.Connection.Open();
    
    da.Fill(ds);
    
    comboBox1.DataSource = da.Table[0];
    comboBox1.DisplayMember = "com";
    comboBox1.ValueMember = "ID";
}
catch (SqlException ex)
{
    MessageBox.Show(ex.Message);
}
finally
{
    comm.Connection.Close();
}