Case when if is time sequence 5 minutes from sql c#

Question

If worker come to company 5 minutes and

 

if (Int32.Parse(queryString) != 0)
               {
                   //provjeravamo da li se radnik mozda prijavio prije 5 minuta, samim tim nema pravo na odjavu a ni na novu prijavu
                   string commanda = "SELECT CASE WHEN (SELECT FLOOR(TIME_TO_SEC(TIMEDIFF(now(),max(VrijemeDolaska)))/60) from prijava_radnika where IdPosjetioc=" + osobaId + ") < 5 THEN 1 ELSE 0 END;";
                   //MessageBox.Show(commanda);
                   int broj = Int32.Parse.Execute(commanda));
                   commanda = "SELECT CASE WHEN (SELECT FLOOR(TIME_TO_SEC(TIMEDIFF(now(),max(VrijemeOdlaska)))/60) from prijava_radnika where IdPosjetioc=" + osobaId + ") < 5 THEN 1 ELSE 0 END;";
                   int broj2 = Int32.Parse.Execute(commanda));
                   //MessageBox.Show(broj.ToString());
                   if (broj == 1 || broj2 == 1)
                   {
                       notificationPanel.BackColor = System.Drawing.ColorTranslator.FromHtml("#FD7400");
                       messageLabel.Text = "Prijava i odjava su blokirani 5 minuta \nza ovog radnika";
                       textBox1.Text = "";
                   }
                   else
                   {   //rest code of app....