How to do a partitioned outer join in BigQuery - sql

Question

I would like to implement the partitioned outer join in BigQuery. To give a concrete example, I'd like to achieve the partitioned outer join as the accepted answer here: https://dba.stackexchange.com/questions/227069/what-is-a-partitioned-outer-join
I understand there are a lot of discussions about this topic, but I can't make it work under BigQuery. I added partition by date after the left table following the same syntax in the answer as follows:
select * from (
select '2019-01-17' as date, 'London' as location, 11 as qty
union all
select '2019-01-15' as date, 'London' as location, 10 as qty
union all
select '2019-01-16' as date, 'Paris' as location, 20 as qty
union all
select '2019-01-17' as date, 'Boston' as location, 31 as qty
union all
select '2019-01-16' as date, 'Boston' as location, 30 as qty
) as sales partition by (date)
right join
(
select 'London' as location
union all
select 'Paris' as location
union all
select 'Boston' as location
)
as loc
using (location)
The target result I'm looking for is:
date qty location
15-JAN-19 NULL Boston
15-JAN-19 10 London
15-JAN-19 NULL Paris
16-JAN-19 30 Boston
16-JAN-19 NULL London
16-JAN-19 20 Paris
17-JAN-19 31 Boston
17-JAN-19 11 London
17-JAN-19 NULL Paris
But I got the following error: Syntax error: Unexpected keyword PARTITION at [11:12]
How can I implement it in BigQuery?

Answer 1

Below is for BigQuery Standard SQL
#standardSQL
SELECT `date`, qty, location
FROM (SELECT DISTINCT `date` FROM sales)
CROSS JOIN loc
LEFT JOIN sales
USING (`date`, location)
You can test, play with above using sample data from your question as in below example
#standardSQL
WITH sales AS (
SELECT '2019-01-17' AS `date`, 'London' AS location, 11 AS qty UNION ALL
SELECT '2019-01-15', 'London', 10 UNION ALL
SELECT '2019-01-16', 'Paris', 20 UNION ALL
SELECT '2019-01-17', 'Boston', 31 UNION ALL
SELECT '2019-01-16', 'Boston', 30
), loc AS (
SELECT 'London' AS location UNION ALL
SELECT 'Paris' UNION ALL
SELECT 'Boston'
)
SELECT `date`, qty, location
FROM (SELECT DISTINCT `date` FROM sales)
CROSS JOIN loc
LEFT JOIN sales
USING (`date`, location)
-- ORDER BY `date`, location
with below result
Row date qty location
1 2019-01-15 null Boston
2 2019-01-15 10 London
3 2019-01-15 null Paris
4 2019-01-16 30 Boston
5 2019-01-16 null London
6 2019-01-16 20 Paris
7 2019-01-17 31 Boston
8 2019-01-17 11 London
9 2019-01-17 null Paris
In case if you need dates to be in 15-JAN-19 format - you below
#standardSQL
SELECT FORMAT_DATE('%d-%b-%y', CAST(`date` AS DATE)) AS `date`, qty, location
FROM (SELECT DISTINCT `date` FROM sales)
CROSS JOIN loc
LEFT JOIN sales
USING (`date`, location)
so result will be
Row date qty location
1 15-Jan-19 null Boston
2 15-Jan-19 10 London
3 15-Jan-19 null Paris
4 16-Jan-19 30 Boston
5 16-Jan-19 null London
6 16-Jan-19 20 Paris
7 17-Jan-19 31 Boston
8 17-Jan-19 11 London
9 17-Jan-19 null Paris