Google BigQuery SQL create multiple "columns" depending on if/then statement?

Question

Is this possible to do in a single query?

I have a sales table that I want to query. The table has details of our sales transactions at the item level, so each record contains fields like: cust_no , item_no , amount , month , year .

I want to summarize the sales info by customer by month by year. I know I can summarize the data like this:

select cust_no,
fiscal_year,
month,
sum(amount) as totalAmt,
group by cust_no, month, fiscal_year

...to get something like this:

cust_no	month	fiscal year	totalAmt
cust_123	1	2022	123.45
cust_345	1	2022	456.78

But I'd like to split out the sales amount depending on whether or not the item_no field is empty or not (because "products" have an item_no where as "services" have a blank item_no).

This is the result I'm going for:

cust_no	month	fiscal year	totalAmt where item_no != ''	totalAmt where item_no = ''
cust_123	1	2022	123.45	222.22
cust_345	1	2022	456.78	111.11

Is there a way to do this in a single query?

Answer 1

May be you can try following query.

select 
    cust_no,
    fiscal_year,
    month,
    SUM(CASE WHEN item_no is NOT NULL THEN totalAmt ELSE 0 END) as total_amt_when_non_null,
    SUM(CASE WHEN item_no is NULL THEN totalAmt ELSE 0 END) as total_amt_when_null
FROM table
group by cust_no, month, fiscal_year