C＃如何从数据库获取数据到文本框

Question

Greetings programmers,

I have a combobox and some textboxes in my windows form connected to a database. My idea is, when the value of the combobox changes the data in the textboxes changes too. Like when I pick a customer ID in the combobox, the textboxes will be loaded with the data of the customer, like the Full name or the address etc. But when I open the Form the combobox disapear's and the textboxes stays empty. I am using Access database and Visual Studio 2012 to code. Here is my code..

C# code :

private void comboBox1_SelectedValueChanged(object sender, EventArgs e)
    {
        string pc = Convert.ToString(comboBox1.SelectedValue);
        string sql = "SELECT * FROM Customer WHERE CustomerID="+ pc;
        Data.Customer_Data(sql, pc);

        txtfullname.Text = Data.fullname;
        txtadress.Text = Data.adress;
        txtcity.Text = Data.city;
        txtemail.Text = Data.email;

    }

And my class called Data:

public static string cs = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + Application.StartupPath + "\\Database1.accdb";
public static string fullname = "";
public static string adress = "";
public static string city = "";
public static string email = "";
public static void Customer_Data(string sql, string pc)
    {
            if (pc == "")
            {
                return;
            }

            else
            {
                OleDbConnection oleDbConnection1 = new System.Data.OleDb.OleDbConnection(cs);
                oleDbConnection1.Open();
                OleDbCommand oleDbCommand1 = new System.Data.OleDb.OleDbCommand(sql,oleDbConnection1);
                OleDbDataReader reader = oleDbCommand1.ExecuteReader();

                if (!reader.Read())
                    return;

                fullname = reader["fullname"].ToString();
                adress = reader["adress"].ToString();
                city = reader["city"].ToString();
                email = reader["email"].ToString();


                oleDbConnection1.Close();
            }
    }

Answer 1

You can try one of the following debugging techniques and see what is happening .

1. After this line Data.Customer_Data(sql, pc); does the data for the properties load properly?
2. Can you also check if there are database values for the corresponding customer id passed ? so that this condition if (!reader.Read()) return; is not executed.
3. Check you page load method( i am sure it doesn't play with the visibility of the combo box, but hey there is no harm in trying).

If none of them mentioned here work then may be some more code will help.