C#

answer 4

Quote:

Extra hint: It's less than (3) and greater than (1).

Can you explain it to me please? I'm just a beginner who learns through some tutorials

List<string> myList = new List<string>();
myList.Add("One");
myList.Add("Two");
myList.Add("Three");
myList.Add("Four");
myList.Add("Five");
foreach (string s in myList)
    {
    Console.WriteLine(s);
    }

One
Two
Three
Four
Five

List<string> myList = new List<string>();
myList.Add("One");
myList.Add("Two");
myList.Add("Three");
myList.Add("Four");
myList.Add("Five");
myList = new List<string>();
foreach (string s in myList)
    {
    Console.WriteLine(s);
}

you are right sir I doubted but after having compiled I realized that the variable s is empty.

...
sql_cmd.Parameters.AddWithValue("@Prix_total_HT", total);
sql_cmd = new OleDbCommand(txtQuery, sql_con);
sql_cmd.ExecuteNonQuery();

really thank you for your advice i will inquire to see if the book is available in french. I did a bit of programming at school but not the csharp, and since it is a langauge that I am passionate about, I decided to take it easy but I really want to know the role of each method used. And for its I thank you again because I followed your advice. But with your permission I would like to send you some project that I have realized thanks to courses on Csharp to just give me your opinion on the presentation of my codes and if there is an improvement to be made.

it does not matter sir I understand you but nevertheless if I have a problem I will post it for a possible help

ago2486 wrote:

'No value given for one or more of the required parameters.'

OriginalGriff wrote:

Look at his code

catch(OleDbException ex)
                      {
                          MessageBox.Show(ex.Source);
                      }

catch(Exception ex)
                      {
                          MessageBox.Show(ex.ToString());
                      }

Hello sir and thank you for the info, I think I saw it when I was doing my research. And it was written only to see the problems with connection to the database. So I would like to know if we could use it only at the connection of the database or not?

thank you sir i will do it now

using (var cmd = sql_con.CreateCommand())
{
    cmd.CommandText = "INSERT INTO Commandes (montant_com) VALUES (@montant_com)";
    cmd.Parameters.AddWithValue("@montant_com", TxtTotalCmd.Text);
    cmd.ExecuteNonQuery();
}

long numCmd;
using (var cmd = sql_con.CreateConnection())
{
    cmd.CommandText = "SELECT MAX(num_com) AS dernier_num FROM Commandes";
    
    object result = cmd.ExecuteScalar();
    if (result is null || Convert.IsDBNull(result))
    {
        numCmd = 0L;
    }
    else
    {
        numCmd = Convert.ToInt64(result);
    }
}

Hello sir and thank you for your help. I did as you advised me but I have a microsoft jet engine error. I will see another tutorial on this subject if I will find a solution ...

ok thank you sir. But there is not much detail except that when I submit the button to add I receive the message microsoft jet engine.

private void BtnAjouter_Click(object sender, EventArgs e)
       {
           int total;
           decimal total_achat;
           //si les champs sont vides
           if (TxtDesignation.Text == "" || TxtPrixUnitaire.Text == "" || TxtQteCmd.Text == "" || TxtQteStock.Text == "" || TxtRefProduit.Text == "")
           {
               MessageBox.Show("Rassurez vous que tous les champs ont bien été rempli.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Information);
           }
           else
           {
               //Vérifier si la valeur saisie est numeric
               if (Int32.TryParse(TxtQteCmd.Text, out int value) && TxtRefProduit.Text != "")
               {
                   //Vérifier si la commande est inferieur ou egale au stock
                   int a = 0;
                   int b = 0;
                   int c;

                   //Convertire les textBox en int
                   int.TryParse(TxtQteCmd.Text.Trim(), out a);
                   int.TryParse(TxtQteStock.Text.Trim(), out b);
                   int.TryParse(TxtPrixUnitaire.Text.Trim(), out c);

                   if (a <= b)
                   {
                       total = a * c;
                       total_achat = 0;

                       try
                       {
                           //setConnection();
                          // sql_con.Open();
                          // using (sql_cmd = sql_con.CreateCommand())
                           {
                              string txtQuery = "INSERT INTO Detail_temp (ref_det, qute_det, Designation, Prix_unitaire_HT, Prix_total_HT) VALUES (@ref_det,@qute_det,@Designation,@Prix_unitaire_HT,@Prix_total_HT)";
                              sql_cmd.Parameters.AddWithValue("@ref_det", TxtRefProduit.Text);
                              sql_cmd.Parameters.AddWithValue("@qute_det", TxtQteCmd.Text);
                              sql_cmd.Parameters.AddWithValue("@Designation", TxtDesignation.Text);
                              sql_cmd.Parameters.AddWithValue("@Prix_unitaire_HT", TxtPrixUnitaire.Text);
                              sql_cmd.Parameters.AddWithValue("@Prix_total_HT", total);
                              sql_cmd = new OleDbCommand(txtQuery, sql_con);
                              sql_cmd.ExecuteNonQuery();
                               //ExecuteQuery(txtQuery);
                           }
                       }
                       catch(OleDbException ex)
                       {
                           MessageBox.Show(ex.Source);
                       }

                       //Création de la requête sql pour inserer des valeurs dans DB
                      //string txtQuery = "INSERT INTO Detail_temp (ref_det, qute_det, Designation, Prix_unitaire_HT, Prix_total_HT) VALUES ('"+ TxtRefProduit.Text+ "', '" + TxtQteCmd.Text + "', '" + TxtDesignation.Text + "', '" + TxtPrixUnitaire.Text + "', '" + total + "')";

                      //ExecuteQuery(txtQuery);

                       try
                       {

                           LoadDB();

                           //ADDITIONNER UNE COLONNE DU DATAGRIDVIEW
                           for (int i = 0; i < dataGridView1.Rows.Count; i++) //Car tu fais une infériorité stricte
                           {
                               total_achat += Convert.ToDecimal(dataGridView1.Rows[i].Cells[4].Value);

                           }
                           TxtTotalCmd.Text = total_achat.ToString();//convertir total_achat en string^pour pouvoir l'afficher dans le textbox
                           TxtDesignation.Text = "";
                           TxtQteCmd.Text = "";
                           TxtPrixUnitaire.Text = "";
                           TxtRefProduit.Text = "";
                           TxtQteCmd.Text = "";
                           //SupDetail_Temp();

                       }

                       catch (OleDbException ex)
                       {
                           MessageBox.Show(ex.Source);
                           sql_con.Close();
                       }
                       finally
                       {
                           sql_con.Close();
                       }

                   }
                   else
                   {
                       MessageBox.Show("Veuillez verifier le stock du produit!!!");
                   }
               }

           }

       }

I followed your advice, sir, regarding possible SQL injection. I may be wrong but I made the parameter request as you told me, but if he has other errors, can you help me please

thank you sir i was afraid i didn't do what you told me.

private void BtnAjouter_Click(object sender, EventArgs e)
       {
           int total;
           decimal total_achat;
           //si les champs sont vides
           if (TxtDesignation.Text == "" || TxtPrixUnitaire.Text == "" || TxtQteCmd.Text == "" || TxtQteStock.Text == "" || TxtRefProduit.Text == "")
           {
               MessageBox.Show("Rassurez vous que tous les champs ont bien été rempli.", "Error", MessageBoxButtons.OK, MessageBoxIcon.Information);
           }
           else
           {
               //Vérifier si la valeur saisie est numeric
               if (Int32.TryParse(TxtQteCmd.Text, out int value) && TxtRefProduit.Text != "")
               {
                   //Vérifier si la commande est inferieur ou egale au stock
                   int a = 0;
                   int b = 0;
                   int c;

                   //Convertire les textBox en int
                   int.TryParse(TxtQteCmd.Text.Trim(), out a);
                   int.TryParse(TxtQteStock.Text.Trim(), out b);
                   int.TryParse(TxtPrixUnitaire.Text.Trim(), out c);

                   if (a <= b)
                   {
                       total = a * c;
                       total_achat = 0;

                       try
                       {
                           //setConnection();
                          // sql_con.Open();
                          // using (sql_cmd = sql_con.CreateCommand())
                           {
                              string txtQuery = "INSERT INTO Detail_temp (ref_det, qute_det, Designation, Prix_unitaire_HT, Prix_total_HT) VALUES (@ref_det,@qute_det,@Designation,@Prix_unitaire_HT,@Prix_total_HT)";
                              sql_cmd.Parameters.AddWithValue("@ref_det", TxtRefProduit.Text);
                              sql_cmd.Parameters.AddWithValue("@qute_det", TxtQteCmd.Text);
                              sql_cmd.Parameters.AddWithValue("@Designation", TxtDesignation.Text);
                              sql_cmd.Parameters.AddWithValue("@Prix_unitaire_HT", TxtPrixUnitaire.Text);
                              sql_cmd.Parameters.AddWithValue("@Prix_total_HT", total);
                              sql_cmd = new OleDbCommand(txtQuery, sql_con);
                              sql_cmd.ExecuteNonQuery();
                               //ExecuteQuery(txtQuery);
                           }
                       }
                       catch(OleDbException ex)
                       {
                           MessageBox.Show(ex.Source);
                       }



                       try
                       {

                           LoadDB();

                           //ADDITIONNER UNE COLONNE DU DATAGRIDVIEW
                           for (int i = 0; i < dataGridView1.Rows.Count; i++) //Car tu fais une infériorité stricte
                           {
                               total_achat += Convert.ToDecimal(dataGridView1.Rows[i].Cells[4].Value);

                           }
                           TxtTotalCmd.Text = total_achat.ToString();//convertir total_achat en string^pour pouvoir l'afficher dans le textbox
                           TxtDesignation.Text = "";
                           TxtQteCmd.Text = "";
                           TxtPrixUnitaire.Text = "";
                           TxtRefProduit.Text = "";
                           TxtQteCmd.Text = "";
                           //SupDetail_Temp();

                       }

                       catch (OleDbException ex)
                       {
                           MessageBox.Show(ex.Source);
                           sql_con.Close();
                       }
                       finally
                       {
                           sql_con.Close();
                       }

                   }
                   else
                   {
                       MessageBox.Show("Veuillez verifier le stock du produit!!!");
                   }
               }

           }

       }