Very useful for testing switches:
MySQL test:
SELECT * FROM menus WHERE (Roles & BIT) = BIT
MySQL set:
UPDATE table SET field = (field | 8 )
MySQL reset:
UPDATE table SET field = ((field | 8 ) ^8)
PHP:
if (($VALIDATION & 8) == 8)
PHP (SET):
function setflag (&$var, $flag, $set = true)
{
$var = $set ? ($var | $flag) : ($var & ~$flag);
}