在表单之间传递值时出错

Question

while passing username and password from form2 to form3 , for the first time when i run the application , the value does not get passed for the first time . however when i re - run the application , it works everytime and the addition is successful , im really new to c# and windows programming so please forgive any poor executions . flow is form1->form2->form3

UPDATE : this is the definition for form 3

  public partial class Form3 : Form
    {
        MySqlConnection connection;
        public string username;
        public string password;
        public Form3(string user,string pass)
        {
            username = user;
            password = pass;
            InitializeComponent();
        }
        private void button1_Click(object sender, EventArgs e)
        {
            MessageBox.Show(username, password);
            string connstring = "server=localhost;user=" + username + ";database=testdb;port=3306;password=" + password + ";";
            connection = new MySqlConnection(connstring);
            connection.Open();
            string query = "INSERT INTO user_books values('" + textBox1.Text + "','" + textBox2.Text + "','" + textBox3.Text + "');";
            MySqlCommand newcommand = new MySqlCommand(query,connection);
            try
            {
                newcommand.ExecuteNonQuery();
                MessageBox.Show("DONE");
            }
            catch (Exception e1)
            {
                MessageBox.Show(e1.ToString());
            }
            connection.Close();

        }

        private void Form3_Load(object sender, EventArgs e)
        {
            MessageBox.Show(username, password);
        }
    } 

and this is form2 :

 public partial class Form2 : Form
    {
        public static MySqlConnection connection;

        public string username;
        public string password;

        public Form2(string user,string pass)
        {
            InitializeComponent();
            this.Text = "MAIN MENU";
            username = user;
            password = pass;
        }

        Form3 form3 = new Form3(username,password);
        private void button1_Click(object sender, EventArgs e)
        {
            MessageBox.Show(username,password);//this lines  no longer gives an empty message box with title Error
            form3.Show();
        }
    }

this is form 1 :

public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            this.Text = "LOGIN";
        }

        MySqlConnection connection;
        Form2 form2;
        private void button1_Click(object sender, EventArgs e)
        {
            string username = textBox1.Text;
            string password = textBox2.Text;

            string connstring = "server=localhost;user=" + username + ";database=testdb;port=3306;password=" + password + ";";

            try
            {
                connection = new MySqlConnection(connstring);
                connection.Open();

                form2 = new Form2(username,password);
                form2.Show();
            }
            catch (Exception e1)
            {
                MessageBox.Show(e1.ToString(), "Exception");
            }
            connection.Close();
        }
    }

using mysql and visual studio 2012

Answer 1

Please give proper names to your forms and drop all static variables.

Move the creation of Form3 into the event handler, so it will get the username/password that are set at the time of the click, not when the class is constructed.