Usually we will use the oldsettings_variablename in the case of updation
for example we need to update the password. In this case we will just compare settings variable value and old settings variable value.if these 2 are not matching then will do the updation
$oldpassword=getenv(‘OLDSETTINGS_password’);// will get the existing password
$newpassword=getenv(‘SETTINGS_password’);// will ge the new password entered.