SQL Days Between Orders

Write a SQL query to calculate the difference in days between consecutive order dates for each customer in a transactions table.

Exclude transactions with a NULL order date. Use transaction_id to break ties when a customer has multiple transactions on the same date.

Output

1. Return one row for each transaction that has a previous valid order for the same customer.
2. Include customer_id, transaction_id, order_date, previous_order_date, and days_since_previous_order.
3. Order by customer_id, order_date, and transaction_id ascending.