如何存储永久布尔标志？

Question

I have created a web app that has 2 control panels. One for the admin and one for the users. I want the users to be able to perform one specific action from their panel only if the admin sets this action "on" (from his panel) and not being able when he sets it "off".

My app also uses a MySql database.

How can I implement it? Is an extra table with only one field a viable solution? Can I do it by reading a file (maybe JSON)?

EDIT: I want the admin to be able to toggle the "on/off" status with a click of a button, so constants are not a solution.

Answer 1

Since you want to store a single value you don't need to use DB. You may simply store this flag in a file as serialized value. Below is simplified example.

define('PERM_FLAG_FILE', 'perm_flag.dat');
$PERM_FLAG = false;

function loadFlag() {
    global $PERM_FLAG;
    return file_exists(PERM_FLAG_FILE)? unserialize(file_get_contents($PERM_FLAG)) : false;
}

function saveFlag() {
    global $PERM_FLAG;
    file_put_contents(PERM_FLAG_FILE, serialize($PERM_FLAG));
}

function setFlag($v) {
    global $PERM_FLAG;
    $PERM_FLAG = (bool)$v;
}