var n = prompt("Is the checklist starting now? (Type either y or n)", "y or n");

        if (n == "y" || n == "Y"){
          alert("The opened date has now been changed!");
        }else if (n = "n" || n == "N"){
          alert("The opened date has not been changed! Sorry to bother you");
        }else{
          alert("You needed to type either n or y, nothing else!");
        }

UPDATE <TABLE>
SET OPENED_DATE = SYSDATE
WHERE...