Creating a new column based on data from an existing column - sql

Question

Consider a system to track repairs. I have a table with customer data and a common id key. I have a second table with a column to show which type of repair part was used on each id key and how many were used. Their definitions are below:
order_information
order_id | cust_last_name
465 Smith
899 Williams
512 Johnson
345 Fenton
122 Bowles
944 Cooper
parts_usage
order_id | part_type | part_quantity
465 Part 1 5
465 Part 2 4
899 Part 1 2
899 Part 2 8
899 Part 3 6
512 Part 3 1
345 Part 2 4
345 Part 3 5
122 Part 2 3
944 Part 1 2
I'd like to run a query for reporting that will return the part's pieces broken out like so:
order_id | Part 1 | Part 2 | Part 3 | Total
465 5 4 9
899 2 8 6 16
512 1 1
345 4 5 9
122 3 3
944 2 2
Is it possible to do this with a query so that my reports can show how many of each part was used on each repair ticket?
As you can see, each order_id can have multiple part types and unique quantities. I want to break the different part types (I have 3 total) into 3 separate columns with their totals listed by order_id.

Answer 1

select order_id, [Part 1], [Part 2], [Part 3], Total
from
(
select oi.order_id
, part_type
, part_quantity
, Total = sum(part_quantity) over (partition by oi.order_id)
from order_information oi
inner join parts_usage pu on oi.order_id = pu.order_id
) as parts
pivot
(
sum(part_quantity) for part_type in ([Part 1], [Part 2], [Part 3])
) as pvt
order by order_id
This works for me.
I have ordered the resultset by order_id as well; there doesn't appear to be a specific order in your example results but it is mentioned in the question details.
You can see the key is to combine the PIVOT with a SUM aggregate window function.
SQL Fiddle with demo.