private void button4_Click(object sender, EventArgs e)
        {
            Auth auth = new Auth();

            if (auth.userLogin(this.login) == true)
            {
                ManagerBooksListForm managerBooksListForm = new ManagerBooksListForm();
                managerBooksListForm.Show();
                this.Close();
            }
            else
            {
                MessageBox.Show("Incorrect username or password!");
            }
        }
 private void button1_Click(object sender, EventArgs e)
 {
     if (!this.managerBookEntry.isValidManagerBookEntry())
     {
         MessageBox.Show("Invalid input!! Try again.");
     }
     else
     {
         try
         {
             MySQLConnector mySQLConnector = new MySQLConnector();
             mySQLConnector.addNewBookEntry(this.managerBookEntry);
             MessageBox.Show("New Book added");
             ManagerBooksListForm managerBooksListForm = new ManagerBooksListForm();
             managerBooksListForm.Show();
             this.Close();
         }
         catch (Exception ex)
         {
             MessageBox.Show("Can not add book. A error occured!");
         }
     }
 }