Question

From my previous question I have solved how to display information from MS Access DB file. The problem is that the sequence number is messing up after I have deleted some entries which I used as sample tries, and now the ID of items are out of order. Here is what it looks now, and following by code I have.

=== Magazine 1 ===
People
Times Inc.
4.95
19.95

=== Magazine 2 ===
Car and Driver
Hachetter Inc.
3.95
19.99

=== Magazine 7 ===
a
b
1
2

Button event (I doubt it’s the codes fault):

    private void btnShowMags_Click(object sender, EventArgs e)
    {
        // Creating new instance of the DisplayMags form.
        DisplayMags displayMags = new DisplayMags();

        // find the path where the executable resides
        string dbPath = Application.StartupPath;

        // Providing a path to the MS Access file.
        string connString = "Provider=Microsoft.Jet.OLEDB.4.0; Data Source="
            + dbPath + @"\..\..\..\..\Magazines.mdb; User Id=admin; Password=";

        // Creating a new connection and assigning it to a variable.
        OleDbConnection conn = new OleDbConnection();
        conn.ConnectionString = connString;

        // Creating a new instance for a command which we will use later.
        OleDbCommand cmd = new OleDbCommand();
        cmd.Connection = conn;

        // declare and instantiate the command
        OleDbCommand cmdMagazines = new OleDbCommand();
        cmdMagazines.CommandText = "select * from magazine";
        cmdMagazines.Connection = conn;

        OleDbDataReader drMagazines;

        try
        {
            // open the connection
            conn.Open();

            // retrieve data from the data source to the data reader
            drMagazines = cmdMagazines.ExecuteReader();

            if (drMagazines.HasRows)
            {
                while (drMagazines.Read())
                {
                    displayMags.txtDisplayMags.Text += "=== Magazine " + 
                        drMagazines.GetValue(0) + " ===" + Environment.NewLine + 
                        drMagazines.GetValue(1) + Environment.NewLine +
                        drMagazines.GetValue(2) + Environment.NewLine +
                        drMagazines.GetValue(3) + Environment.NewLine +
                        drMagazines.GetValue(4) + Environment.NewLine + 
                        Environment.NewLine;
                }
            }
        }
        catch (Exception ex)
        {
            // Displaying any errors that might have occured.
            MessageBox.Show("Error opening the connection: " + ex.Message);
        }
        finally
        {
            // Closing connection after task was completed.
            conn.Close();
        }

        // Displaying DisplayMags form, assuring that earlier form
        // will not be accessible. Show() let us access all forms.
        displayMags.ShowDialog();
    }

How can I make the sequence number to appear in order?

EDIT I will count all entries this way:

        try
        {
            // open the connection
            conn.Open();

            // retrieve data from the data source to the data reader
            drMagazines = cmdMagazines.ExecuteReader();

            int i = 0;

            if (drMagazines.HasRows)
            {
                while (drMagazines.Read())
                {
                    i++;

                    displayMags.txtDisplayMags.Text += "=== Magazine " + 
                        i + " ===" + Environment.NewLine + 
                        drMagazines.GetValue(1) + Environment.NewLine +
                        drMagazines.GetValue(2) + Environment.NewLine +
                        drMagazines.GetValue(3) + " / issue" + Environment.NewLine +
                        drMagazines.GetValue(4) + " / year" + Environment.NewLine + 
                        Environment.NewLine;
                }
            }
        }

Answer 1

They are not “sequence numbers” but “primary keys”.

Keys should never change so Yes, deleting rows will produce gaps. There is no built-in mechanism to renumber.