Vtiger - Editing the Picklistutils.php script to select certain values for custom fields

Question

I want to modify the sql statement that selects the picklist values for my custom field

Modified the custom field table by adding a createdtime column and updated the values. I added custom code to the functions in the picklistutils.php:

if ($adb->$fieldName == cf_879) {
    $sql = 'SELECT * FROM vtiger_cf_879 WHERE createdtime LIKE '2019-08%';
    $result = $adb-> query($sql);
    $count = $adb->num_rows($result);
}

The pick list values should only show the fields in the database with the created time in 2019-08