sum for each customers and create a summary table - sql

Question

I have Table A :
Customer_ID Card_number Amount_of_deals
1 221 100
1 222 350
2 223 200
3 334 700
3 344 650
4 544 1500
I want to create a new table with ranges of the amount and count of customers in each range.
the new table should be :
Range Number_of_customers
0-500 2
500-1000 0
1000-1500 2
How can I create this table?
Thanks in advance

Answer 1

You can use case expression with group by :
select (case when amount >= 0 and amount <= 500 then '0-500'
when amount > 500 and amount <= 1000 then '501-1000'
when amount > 1000 and amount <= 1500 then '1001-1500'
else '1500+'
end) as Range, count(distinct custmore_id) as Number_of_customers
from table t
group by (case when amount >= 0 and amount <= 500 then '0-500'
when amount > 500 and amount <= 1000 then '501-1000'
when amount > 1000 and amount <= 1500 then '1001-1500'
else '1500+'
end);
If you are using SQL Server then you can use apply & use SELECT .. INTO statement :
select range, count(distinct custmore_id) as Number_of_customers
into new_table
from table t cross apply
( values (case when amount >= 0 and amount <= 500 then '0-500'
when amount > 500 and amount <= 1000 then '501-1000'
when amount > 1000 and amount <= 1500 then '1001-1500'
else '1500+'
end)
) tt(range)
group by range;

Answer 2

Because you want 0 values, you need a left join somewhere. I would recommend:
select v.range, count(c.customer_id)
from (values ('0-500', 0, 500),
('501-1000', 500, 1000),
('1001-1500', 1000, 1500)
) v(range, lo, hi) left join
(select customer_id, sum(amount_of_deals) as num
from a
group by customer_id
) c
on c.num > v.lo and c.num <= v.hi
group by v.range
order by min( v.lo );
Here is a db<>fiddle.