Postgres - partial pivot with crosstab - postgresql

Question

I'm struggling, and knowing the terminology to search for the answer is likely my problem as I can't imagine this is an edge case.
dbfiddle available
I have a table in Postgres 9.4:
CREATE TABLE test (
id serial PRIMARY KEY, cust_id INTEGER,
category VARCHAR, key INTEGER, value INTEGER
);
INSERT INTO test (cust_id, category, key, value)
VALUES
(1, 'alpha', 0,300),(1, 'bravo', 0,150),(1, 'alpha', 1,300),
(1, 'bravo', 1,200),(1, 'alpha', 2,300),(1, 'bravo', 2,250),
(2, 'alpha', 0,301),(2, 'bravo', 0,151),(2, 'alpha', 1,301),
(2, 'bravo', 1,201),(2, 'alpha', 2,301),(2, 'bravo', 2,251),
(3, 'alpha', 0,302),(3, 'bravo', 0,152),(3, 'alpha', 1,302),
(3, 'bravo', 1,202),(3, 'alpha', 2,302),(3, 'bravo', 2,252);
id | cust_id | category | key | value
----+---------+----------+-----+-------
1 | 1 | alpha | 0 | 300
2 | 1 | bravo | 0 | 150
3 | 1 | alpha | 1 | 300
4 | 1 | bravo | 1 | 200
5 | 1 | alpha | 2 | 300
6 | 1 | bravo | 2 | 250
7 | 2 | alpha | 0 | 301
8 | 2 | bravo | 0 | 151
9 | 2 | alpha | 1 | 301
10 | 2 | bravo | 1 | 201
11 | 2 | alpha | 2 | 301
12 | 2 | bravo | 2 | 251
13 | 3 | alpha | 0 | 302
14 | 3 | bravo | 0 | 152
15 | 3 | alpha | 1 | 302
16 | 3 | bravo | 1 | 202
17 | 3 | alpha | 2 | 302
18 | 3 | bravo | 2 | 252
(18 rows)
I'd like to query the results to look like the following:
cust_id | category | 0 | 1 | 2
---------+----------+-----+-----+-----
1 | alpha | 300 | 300 | 300
1 | bravo | 150 | 200 | 250
2 | alpha | 301 | 301 | 301
2 | bravo | 151 | 201 | 251
3 | alpha | 302 | 302 | 302
3 | bravo | 152 | 202 | 252
(6 rows)
I've tried:
SELECT
*
FROM
crosstab(
'SELECT cust_id,category,key,value FROM test ORDER BY cust_id,category,key',
$$values ('0'::INT),
('1'::INT),
('2'::INT) $$
) AS ct (
"cust_id" INT, "category" TEXT, "0" INT,
"1" INT, "2" INT
);
which nets me (lacking the bravo category rows and uses bravo values for columns 1,2,3):
cust_id | category | 0 | 1 | 2
---------+----------+-----+-------
1 | alpha | 150 | 200 | 250
2 | alpha | 151 | 201 | 251
3 | alpha | 152 | 202 | 252
(2 rows)
I get closer with the following by removing the cust_id field and limiting to a single id:
SELECT
*
FROM
crosstab(
'SELECT category,key,value FROM test WHERE cust_id = 1 ORDER BY category,key',
$$values ('0'::INT),
('1'::INT),
('2'::INT) $$
) AS ct (
"category" TEXT, "0" INT,
"1" INT, "2" INT
);
but this only gives the result for a single cust_id, but I need this for all customers:
category | 0 | 1 | 2
----------+-----+-------
alpha | 300 | 300 | 300
bravo | 150 | 200 | 250
(2 rows)
https://dbfiddle.uk/?rdbms=postgres_9.5&fiddle=2c75cf9a1b18bb980ddd72953235d54e

Answer 1

here is one way :
select cust_id , category
, max(case when key = 0 then value end) "0"
, max(case when key = 1 then value end) "1"
, max(case when key = 2 then value end) "2"
from test
group by cust_id , category
order by cust_id , category