group by and aggregate from tall to wide data in bigquery sql - google-bigquery

Question

Hi I want to aggregate group by and change it from tall to wide data in bigquery, how do I do so? I have a lot of sources and here's a sample data.
Here's the table
date
source
price
id
2022-01-01
A
2
1
2022-01-02
A
2
1
2022-01-03
A
4
1
2022-01-04
A
4
1
2022-01-01
B
1
1
2022-01-02
B
1
1
2022-01-03
B
3
1
2022-01-04
B
3
1
2022-01-01
A
2
2
2022-01-02
A
2
2
2022-01-03
A
4
2
2022-01-04
A
4
2
2022-01-01
B
1
2
2022-01-02
B
1
2
2022-01-03
B
3
2
2022-01-04
B
3
2
into
fields of min from price from all source for group by id and min price per source group by id
id
minPrice
minPriceSourceA
minPriceSourceB
1
2.5
3
2
2
2.5
3
2
Here's my current code
with Amin as
(
select
id,source,
min(price) min price
from table
where source ="A"
group by 1,2
),
Bmin as
(
select
id,source,
min(price) min price
from table
where source ="B"
group by 1,2
),
select
t1.id,t1.minprice,
Amin.minprice minPriceSourceA,
Bmin.minprice minPriceSourceB
from(
select
id,source,
min(price) minprice
from table
group by 1,2) t1
left join Amin on t1.id=Amin.id
left join Bmin on t1.id=Bmin.id
The problem is I have over 100 sources and id, if I do query manually the code will be very long. Is there an efficient way to do this?

Answer 1

You can use PIVOT to transpose rows into columns and get the MIN of a list of columns at once:
with sample as (
select "2022-01-01" as date, "A" as source, 2 as price, "1" as id
UNION ALL
select "2022-01-02" as date, "A" as source, 1 as price, "1" as id
UNION ALL
select "2022-01-04" as date, "B" as source, 1 as price, "1" as id
UNION ALL
select "2022-01-04" as date, "A" as source, 2 as price, "2" as id
UNION ALL
select "2022-01-04" as date, "A" as source, 4 as price, "2" as id
UNION ALL
select "2022-01-04" as date, "B" as source, 3 as price, "2" as id
),
min_by_source as (
SELECT * FROM
(SELECT id, source, price FROM sample)
PIVOT(MIN(price) AS minPrice FOR source IN ('A', 'B')) -- add here the others sources
),
min_global as (
SELECT id, MIN(price) AS minPrice
FROM sample
GROUP BY id
)
SELECT *
FROM min_global
JOIN min_by_source USING (id)
Output:
id minPrice minPrice_A minPrice_B
1 1 1 1
2 2 2 3

Answer 2

Consider below option
select * from (
select * except(date),
avg(price) over(partition by id) avgPrice,
min(price) over(partition by id) minPrice
from your_table)
pivot (min(price) minPriceSource for source in ('A', 'B'))
if applied to sample data in your question - output is
The problem is I have over 100 sources and id, if I do query manually the code will be very long. Is there an efficient way to do this?
Use below dynamic version
execute immediate (select '''
select * from (
select * except(date),
avg(price) over(partition by id) avgPrice,
min(price) over(partition by id) minPrice
from your_table)
pivot (min(price) minPriceSource for source in (''' || string_agg(distinct '"' || source || '"') || '''))
'''
from your_table
)