How to Monitor Repeat Purchase Behavior Using Google Data Studio and BigQuery | by Noemi Ramiro | Towards Data Science

SELECT *,
CASE WHEN customer_seq > 1 THEN 'Repeat Customer'
ELSE 'New Customer'
END AS RepeatPurchase
FROM (
    SELECT  *,
    RANK() OVER (PARTITION BY CustomerID ORDER BY date) AS customer_seq
    FROM online_retail
)