// Add button to create customer entries
        // Does not allow empty/duplicate names and email
        private void CreateButton(object sender, EventArgs e)
        {
            //open database connection
            CustomerDB.Open();

            //create sql command string variable
            SqlCommand command = CustomerDB.CreateCommand();
            command.CommandType = CommandType.Text;

            if (string.IsNullOrWhiteSpace(NameText.Text) || string.IsNullOrWhiteSpace(NumberText.Text) || string.IsNullOrWhiteSpace(EmailText.Text))
            {
                MessageBox.Show("Please enter a name, phone number, and email.");
                CustomerDB.Close();
            }

            else
            {
                Account account = new Account();
                command.CommandText = "Select CustomerName from Customer where CustomerName = '" + NameText.Text + "'";
                account.Name = (string)command.ExecuteScalar();

                command.CommandText = "Select Email from Customer where Email = '" + EmailText.Text + "'";
                account.Email = (string)command.ExecuteScalar();

                if (NameText.Text == account.Name)
                {
                    MessageBox.Show("This customer already exists.");
                    CustomerDB.Close();
                }

                else if (EmailText.Text == account.Email)
                {
                    MessageBox.Show("This email has already been used.");
                    CustomerDB.Close();
                }

                else
                {
                    //insert 'new' Customer data entries
                    command.CommandText = "insert into Customer values('" + NameText.Text + "','" + NumberText.Text + "','" + EmailText.Text + "')";

                    command.ExecuteNonQuery();
                    CustomerDB.Close();
                    live_update();
                    MessageBox.Show("Customer data added.");
                }
            }
        }
        // Delete button - only deletes by CustomerID
        private void DeleteButton(object sender, EventArgs e)
        {
            //open database connection
            CustomerDB.Open();

            //create sql command string variable
            SqlCommand command = CustomerDB.CreateCommand();

            command.CommandType = CommandType.Text;

            Account account = new Account();
            command.CommandText = "Select CustomerID from Customer where CustomerID = '" + IDText.Text + "'";
            account.ID = command.ExecuteScalar().ToString();

            if (string.IsNullOrWhiteSpace(IDText.Text))
            {
                MessageBox.Show("Please enter a CustomerID to delete an entry.");
                CustomerDB.Close();
            }

            else if (string.IsNullOrWhiteSpace(account.ID))
            {
                MessageBox.Show("Customer does not exist. Delete not performed.");
                CustomerDB.Close();
            }
            else
            {
                //delete Customer data by CustomerID
                command.CommandText = "delete from Customer where CustomerID = '" + IDText.Text + "'";
                command.ExecuteNonQuery();
                CustomerDB.Close();
                live_update();
                MessageBox.Show("Customer data deleted.");
            }
        }