Creating column for every group in group by - sql

Question

Suppose I have a table T which has entries as follows:
id | type | value |
-------------------------
1 | A | 7
1 | B | 8
2 | A | 9
2 | B | 10
3 | A | 11
3 | B | 12
1 | C | 13
2 | C | 14
For each type, I want a different column. Since the number of types is exhaustive, I would like all different types to be enumerated and a corresponding column for each. I wanted to make id a primary key for the table.
So, the desired output is something like:
id | A's value | B's value | C's value
------------------------------------------
1 | 7 | 8 | 13
2 | 9 | 10 | 14
3 | 11 | 12 | NULL
Please note that this is a simplified version. The actual table T is derived from a much bigger table using group by. And for each group, I would like a separate column. Is that even possible?

Answer 1

Use conditional aggregation:
select id,
max(case when type = 'A' then value end) as a_value,
max(case when type = 'B' then value end) as b_value,
max(case when type = 'C' then value end) as c_value
from t
group by id;

Answer 2

I'd recommend looking into the PIVOT function:
https://docs.snowflake.com/en/sql-reference/constructs/pivot.html
The main blocker with this function though is the list of values for the pivot_column needs to be
pre-determined. To do this, I normally use the LISTAGG function:
https://docs.snowflake.com/en/sql-reference/functions/listagg.html
I've included a query below to show you how to build that string,
and doing this together in a script like
Python or even a Stored Procedure should be fairly straightforward (build the pivot_column, build the aggregate/pivot command, execute the aggregate/pivot command).
I hope this helps...Rich
CREATE OR REPLACE TABLE monthly_sales(
empid INT,
amount INT,
month TEXT)
AS SELECT * FROM VALUES
(1, 10000, 'JAN'),
(1, 400, 'JAN'),
(2, 4500, 'JAN'),
(2, 35000, 'JAN'),
(1, 5000, 'FEB'),
(1, 3000, 'FEB'),
(2, 200, 'FEB'),
(2, 90500, 'FEB'),
(1, 6000, 'MAR'),
(1, 5000, 'MAR'),
(2, 2500, 'MAR'),
(2, 9500, 'MAR'),
(1, 8000, 'APR'),
(1, 10000, 'APR'),
(2, 800, 'APR'),
(2, 4500, 'APR');
SELECT *
FROM monthly_sales
PIVOT(SUM(amount)
FOR month IN ('JAN', 'FEB', 'MAR', 'APR'))
AS p
ORDER BY empid;
SELECT LISTAGG( DISTINCT ''''||month||'''', ', ' )
FROM monthly_sales;