private void SignUpButtonSignUpForm_Click(object sender, EventArgs e) { // Get connection string from configuration file. var connectionString = ConfigurationManager.ConnectionStrings["conString"].ConnectionString; MySqlConnection connection = new MySqlConnection(connectionString); connection.Open(); // SQL queries. string query = "INSERT INTO Users(Username, Password) VALUES(@username, @password)"; string userQuery = "SELECT count(*) FROM Users WHERE Username = @usernamecheck"; MySqlCommand cmd = new MySqlCommand(query, connection); MySqlCommand checkUserExists = new MySqlCommand(userQuery, connection); checkUserExists.Parameters.AddWithValue("@usernamecheck", usernameTextBoxSignUpForm.Text); int UserExists = Convert.ToInt32(checkUserExists.ExecuteScalar()); // If the username entered is taken already, display a message to the user. if (UserExists > 0) { MessageBox.Show("Username is already in use!\nPlease choose another", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error); usernameTextBoxSignUpForm.Clear(); passwordTextBoxSignUpForm.Clear(); confirmPasswordTextboxSignUpForm.Clear(); usernameTextBoxSignUpForm.Focus(); } else { // Checks for blank text boxes and display a message to the user. if (usernameTextBoxSignUpForm.Text == "" || passwordTextBoxSignUpForm.Text == "" || confirmPasswordTextboxSignUpForm.Text == "") { MessageBox.Show("Please fill in all details", "Error", MessageBoxButtons.OK, MessageBoxIcon.Error); return; } if (passwordTextBoxSignUpForm.Text.Equals(confirmPasswordTextboxSignUpForm.Text)) { // Add username and password to database. cmd.Parameters.AddWithValue("@username", usernameTextBoxSignUpForm.Text); cmd.Parameters.AddWithValue("@password", passwordTextBoxSignUpForm.Text); cmd.ExecuteNonQuery(); MessageBox.Show("Sign up Successful!\n\nHello " + usernameTextBoxSignUpForm.Text + "\n"); connection.Close(); LoginForm loginForm = new LoginForm(); // Close current form and open login form in same position. this.Hide(); loginForm.StartPosition = FormStartPosition.Manual; loginForm.Location = Location; loginForm.Size = Size; loginForm.Show(); } else { // If passwords don't match show message to user. MessageBox.Show("Passwords do not match!"); usernameTextBoxSignUpForm.Clear(); passwordTextBoxSignUpForm.Clear(); confirmPasswordTextboxSignUpForm.Clear(); } } }