9. Number of high spend customers by month medium

Instruction

• Write a query to count the number of customers who spend more than > $20 by month
• You can use EXTRACT(YEAR from timestamp_col) and EXTRACT(MONTH from timestamp_col) to get year and month from a timestamp column.
• Hint: a customer's spend varies every month.

Table: payment sample data

---

Movie rental payment transactions table

   col_name   | col_type
--------------+--------------------------
 payment_id   | integer
 customer_id  | smallint
 staff_id     | smallint
 rental_id    | integer
 amount       | numeric
 payment_ts   | timestamp with time zone

Sample results

year	mon	num_hp_customers
2020	2	158
2020	5	520