hierarchy – CONNECT BY PRIOR Query

I know I have to use CONNECT BY PRIOR in this query, but I’m not sure how to implement it.

We have customers who purchase monthly subscriptions, and those get auto-renewed each month. We have a log table which can show what your current order ID is, and what your previous order ID is. So, table records could like like this:

CUSTOMER ID: 1     ORDER ID: 123   PREV_ORDER_ID:       STATUS: Complete
CUSTOMER ID: 1     ORDER ID: 456   PREV_ORDER_ID: 123   STATUS: Complete
CUSTOMER ID: 1     ORDER ID: 789   PREV_ORDER_ID: 456   STATUS: Complete
CUSTOMER ID: 1     ORDER ID: 888   PREV_ORDER_ID: 789   STATUS: Complete
CUSTOMER ID: 1     ORDER ID: 999   PREV_ORDER_ID: 888   STATUS: Active

I am looking to count how many customers have had at least 13 months of consecutive subscriptions, with no gaps with the most recent subscription will have an “Active” status. If there is a break in subscriptions, the PREV_ORDER_ID will be NULL.

Hoping to do this in a query, and not having to write an anonymous block for it.

Many thanks!