How to use ORDER BY correctly?

Question

PHP

Hello!
There are two tables:

When selecting from them, it is necessary to sort by status (status), by date of modification (o.date_modified) and by what the user additionally selects (for example, by customer).
Used the following query:
SELECT o.order_id, CONCAT(o.firstname, ' ', o.lastname) AS customer, (SELECT os.name FROM oc_order_status os WHERE os.order_status_id = o.order_status_id AND os.language_id = '1') AS status, o.total, o.currency_code, o.currency_value, o.date_added, o.date_modified FROM `oc_order` o WHERE o.order_status_id > '0' ORDER BY status ASC, o.date_modified ASC, customer
ASC I get sorted by status and date, but not by customer

Answer 1

ORDER BY status ASC, o.date_modified ASC, customer ASC - such a record filters by status, if there are identical statuses, then they will be sorted by date, and if the dates are the same, then they will be sorted by customer. Sort first by customer, then by date_modified

Answer 2

o.date_modified - in seconds, it will sort by customer only if there are multiple records with the same date_modified

Answer 3

use DATE(o.date_modified) to have it sorted by day (this will exclude hours and minutes)