private void textBox_kartyaszam_TextChanged(object sender, EventArgs e)
{
string value = textBox_kartyaszam.Text;
OracleManager oracleManager = new OracleManager();
if (!oracleManager.CheckData(value))
{
textBox_kartyaszam.BackColor = Color.Red;
}
else
{
textBox_kartyaszam.BackColor = Color.White;
}
}
