MySQL 8.0

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select version();


version()


8.0.30


-- -- create
create table table1(
  customer_id int,
  item_id int,
  item_number int,
  item_price decimal(12, 2),
  item_name varchar(20)
);

-- -- insert
insert into table1
values(1,	1,	40,	11.55,	'spoon'),
(1,	1,	30,	11.55,	'spoon'),
(2,	1,	14,	9.00,	'spoon'),
(2,	2,	50,	40.00,	'table'),
(3,	3,	10,	5.00,	'book'),
(3,	3,	20,	6.00,	'book')


Records: 6  Duplicates: 0  Warnings: 0


select * from table1


customer_id
item_id
item_number
item_price
item_name


1
1
40
11.55
spoon

1
1
30
11.55
spoon

2
1
14
9.00
spoon

2
2
50
40.00
table

3
3
10
5.00
book

3
3
20
6.00
book


select customer_id, sum(item_number * item_price) as amount_spent_1m -- , item_name as top_item_1m
from table1
group by customer_id


customer_id
amount_spent_1m


1
808.50

2
2126.00

3
170.00

customer_id	item_id	item_number	item_price	item_name
1	1	40	11.55	spoon
1	1	30	11.55	spoon
2	1	14	9.00	spoon
2	2	50	40.00	table
3	3	10	5.00	book
3	3	20	6.00	book