private void btnGuncelle_Click(object sender, EventArgs e)
        {
            if (txtID.Text == "")
            {
                MessageBox.Show("ID cannot be empty.");
                return;
            }

            int id = Convert.ToInt32(txtID.Text);

            string lastName = txtLastName.Text;

            string firstName = txtFirstName.Text;

            if (txtAge.Text == "")
            {
                txtAge.Text = "0";
            }

            int age = Convert.ToInt32(txtAge.Text);

            try
            {
                TestDLLClass testDLLClass = new TestDLLClass();
                testDLLClass.guncelle(id, lastName, firstName, age);
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Exception");
            }
        }
        protected void btnGuncelle_Click(object sender, EventArgs e)
        {
            if (txtID.Text == "")
            {
                showError("ID cannot be empty");
                return;
            }

            int    id        = Convert.ToInt32(txtID.Text);
            string lastName  = txtLastName.Text;
            string firstName = txtFirstName.Text;

            if (txtAge.Text == "")
            {
                txtAge.Text = "0";
            }
            int age = Convert.ToInt32(txtAge.Text);

            try
            {
                TestDLLClass testDLLClass = new TestDLLClass();
                testDLLClass.guncelle(id, lastName, firstName, age);
                lblHata.Text = "";
            }
            catch (Exception ex)
            {
                showError(ex.Message);
                return;
            }
        }
        protected void btnGetir_Click(object sender, EventArgs e)
        {
            if (txtID.Text == "")
            {
                showError("ID cannot be empty");
                return;
            }

            string id = txtID.Text;

            try
            {
                TestDLLClass testDLLClass = new TestDLLClass();
                DataTable    kayit        = testDLLClass.getir(id);
                txtID.Text        = (kayit.Rows[0]["ID"].ToString());
                txtLastName.Text  = (kayit.Rows[0]["LastName"].ToString());
                txtFirstName.Text = (kayit.Rows[0]["FirstName"].ToString());
                txtAge.Text       = (kayit.Rows[0]["Age"].ToString());
                lblHata.Text      = "";
            }
            catch (Exception ex)
            {
                showError(ex.Message);
            }
        }
        private void btnGetir_Click(object sender, EventArgs e)
        {
            if (txtID.Text == "")
            {
                MessageBox.Show("ID cannot be empty.");
                return;
            }
            string id = txtID.Text;

            try
            {
                TestDLLClass testDLLClass = new TestDLLClass();
                DataTable    kayit        = testDLLClass.getir(id);
                txtID.Text        = (kayit.Rows[0]["ID"].ToString());
                txtLastName.Text  = (kayit.Rows[0]["LastName"].ToString());
                txtFirstName.Text = (kayit.Rows[0]["FirstName"].ToString());
                txtAge.Text       = (kayit.Rows[0]["Age"].ToString());
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message, "Exception");
            }
        }