基于列的 SQL 中的 SUM 值

Question

I have a table like below:

I want to transform the data so that the end product actually looks like this:

This is easily done within Excel but i would like to be able to do this via SQL so i can automate a report.

I have tried the below code which doesn't work:

SELECT 
SKU,
SUM(totals,ordered = 'Web') as Web_orders,
SUM(totals,ordered = 'App') as App_orders

FROM A

GROUP BY SKU

Answer 1

This will work:

SELECT 
SKU,
SUM(totals) filter (where ordered='web') as Web_orders,
SUM(totals) filter (where ordered='app') as App_orders
FROM A

GROUP BY SKU
ORDER by SKU;

If you want the uppercase letters you need to surround the column names with "".

Answer 2

You can make use of case expressions:

SELECT
  sku,
  SUM(case when ordered = 'web' then totals else 0 end) as "web",
  SUM(case when ordered = 'app' then totals else 0 end) as "app"
FROM A
GROUP BY sku