private void LoginButton_Click(object sender, EventArgs e)
        {
            if (EmailLoginTextbox.Text.Equals("") || PasswordLoginTextbox.Text.Equals(""))
            {
                toolTip.Active = true;
                toolTip.SetToolTip(this.LoginButton, "Missing Inputs!");
                return;
            }

            if (!IsValidEmail(EmailLoginTextbox.Text))
            {
                toolTip.Active = true;
                toolTip.SetToolTip(this.LoginButton, "Invalid email format!");
                return;
            }

            dt = dbconn.Select("SELECT `users`.`name` AS name, `users`.`surname` AS surname, `users`.`email` AS email, `users`.`password` AS password FROM `bookstore_schema`.`users` WHERE email = '" + EmailLoginTextbox.Text + "' AND password = '******';");

            if (dt.Rows.Count == 0)
            {
                toolTip.Active = true;
                toolTip.SetToolTip(this.LoginButton, "Wrong credentials!");
                return;
            }

            entryForm = new EntryForm(dt.Rows[0]["name"].ToString(), dt.Rows[0]["surname"].ToString(), dt.Rows[0]["email"].ToString());
            this.Hide();
            entryForm.Show();
        }
        private void SignUpButton_Click(object sender, EventArgs e)
        {
            foreach (TextBox c in SignUpPanel.Controls.OfType <TextBox>())
            {
                if (c.Text.Equals(""))
                {
                    toolTip.Active = true;
                    toolTip.SetToolTip(this.SignUpButton, "Missing Inputs!");
                    return;
                }
            }

            if (!IsValidEmail(emailSignUpTextBox.Text))
            {
                toolTip.Active = true;
                toolTip.SetToolTip(this.SignUpButton, "Invalid email format!");
                return;
            }

            dt = dbconn.Select("SELECT `users`.`email` AS email FROM `bookstore_schema`.`users` WHERE email = '" + EmailLoginTextbox.Text + "';");

            if (dt.Rows.Count != 0)
            {
                toolTip.Active = true;
                toolTip.SetToolTip(this.SignUpButton, "Email already exists!");
                return;
            }

            if (!passwordSignUpTextBox.Text.Equals(passwordConfirmSignUpTextbox.Text))
            {
                toolTip.Active = true;
                toolTip.SetToolTip(this.SignUpButton, "Wrong password confirmation!");
                return;
            }

            message = dbconn.ExecuteNonQuery("INSERT INTO `bookstore_schema`.`users` (`name`, `surname`, `password`, `email`, `type`) VALUES ('" + nameSignUpTextBox.Text + "', '" + surnameSignUpTextBox.Text + "', '" + passwordSignUpTextBox.Text + "', '" + emailSignUpTextBox.Text + "', 'user');");
            if (!message.Equals("OK"))
            {
                MessageBox.Show("Email already exists!", "Duplicate Entry", MessageBoxButtons.OK, MessageBoxIcon.Information);
                return;
            }

            entryForm = new EntryForm(nameSignUpTextBox.Text, surnameSignUpTextBox.Text, emailSignUpTextBox.Text);
            this.Hide();
            entryForm.Show();
        }