added subquery

Author: letsdeepchat

SUBQUERIES/1321. Restaurant Growth.sql

@@ -0,0 +1,6 @@
+SELECT visited_on, 
+       SUM(amount) OVER (ORDER BY visited_on ROWS BETWEEN 6 PRECEDING AND CURRENT ROW) AS amount,
+       ROUND(SUM(amount) OVER (ORDER BY visited_on ROWS BETWEEN 6 PRECEDING AND CURRENT ROW) / 7, 2) AS average_amount
+FROM customer
+WHERE visited_on >= (SELECT DATE_ADD(MIN(visited_on), INTERVAL 6 DAY) FROM customer)
+ORDER BY visited_on;