SQL - How to do this group by query

When I run the following SQL, I got an error:

> select service_account_id

  2 from service_consumptions
  3 where max (read_date) < sysdate - 30   4 group by service_account_id
  5 order by service_account_id;
where max (read_date) < sysdate - 30

      *
ERROR at line 3:
ORA-00934: group function is not allowed here

I only want to get those items which read_date is less than 30 days to the system date.

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Best regards, Received on Sun Jun 27 1999 - 18:42:02 CDT