Detect Impossible Order Status Transitions

What you will practice

Sequence status events by occurred_at then event_id. Allowed adjacent transitions are CREATED→PAID, CREATED→CANCELLED, PAID→SHIPPED, PAID→CANCELLED, SHIPPED→DELIVERED, and duplicate same-status events. Return every invalid transition with order_id, previous_status, current_status and current_event_id. Return columns: order_id, previous_status, current_status, current_event_id.

Difficulty

Expert

SQL concept

CTE