每月 Select 行产品事件并将其连接到另一个表中

Question

I have a Biguery table like this:

Product	Date	Event
A	2022-03-08	M
A	2022-03-25	P
A	2022-02-03	S
B	2022-02-20	Q
B	2022-03-10	R

Based on current date (2022-03-29), I need to insert in another Bigquery table in this format:

Product	Month-0	Month-1
A	M;P	S
B	R	Q

I appreciate if you can help me.

Regards.

Answer 1

using pivot and string_agg will do this aggregation

With tbl as
(SELECT "A" Product , date "2022-03-08" date, "M" event
Union ALL SELECT "A", "2022-03-25", "P"
Union ALL SELECT "A", "2022-02-03", "S"
Union ALL SELECT "B", "2022-02-20", "Q"
Union ALL SELECT "B", "2022-03-10", "R"
)

SELECT *, 
from 
(SELECT Product,event, date_diff(current_date(),date,month) as diff
from tbl)
PIVOT(string_agg(event,";") month FOR diff IN (0,1,2)  )

Answer 2

Consider below approach

execute immediate (select '''
select * from your_table
pivot(string_agg(event,";") month for date_diff(current_date(),date,month) in (''' || string_agg('' || value) || '''))
'''
from (
  select max(date_diff(current_date(),date,month)) max_diff from your_table
), unnest(generate_array(0, max_diff)) value
)       

if applied to sample data in your question - output is