convert subquery to use Cases and Join - oracle

Question

I have a query which is working fine. I want to convert it to use Cases and Join.
SELECT id, Ticket_id, serial_no, operator,
(SELECT value FROM Forms_Details where FORM_ID = cv.id and status = 'ACTIVE' and key = 'COMPUTER_TYPE') as COMPUTER_TYPE,
(SELECT value FROM Forms_Details where FORM_ID = cv.id and status = 'ACTIVE' and key = 'BRAND') as BRAND,
(SELECT value FROM Forms_Details where FORM_ID = cv.id and status = 'ACTIVE' and key = 'MODEL') as MODEL,
status, datetime
FROM Form cv
where status = 'ACTIVE' order by id desc;

Answer 1

If you want to join, then join. What keeps you from doing so?
SELECT
f.id,
f.Ticket_id,
f.serial_no,
f.operator,
ct.value AS computer_type,
b.value AS brand,
m.value AS model,
f.status,
f.datetime
FROM form f
LEFT JOIN forms_details ct ON ct.form_id = f.id AND ct.status = 'ACTIVE' AND ct.key = 'COMPUTER_TYPE'
LEFT JOIN forms_detailswhere b ON b.form_id = f.id AND b.status = 'ACTIVE' AND b.key = 'BRAND'
LEFT JOIN forms_detailswhere m ON m.form_id = f.id AND m.status = 'ACTIVE' AND m.key = 'MODEL'
WHERE f.status = 'ACTIVE'
ORDER BY f.id DESC;
Or, in order not to read the same table twice, you can use conditional aggregation to get the values from the table:
SELECT
f.id,
f.Ticket_id,
f.serial_no,
f.operator,
ct.value AS computer_type,
fdw.brand,
fdw.model,
f.status,
f.datetime
FROM form f
LEFT JOIN forms_details ct ON ct.form_id = f.id AND ct.status = 'ACTIVE' AND ct.key = 'COMPUTER_TYPE'
LEFT JOIN
(
SELECT
form_id,
MAX(CASE WHEN key = 'BRAND' THEN value END) AS brand,
MAX(CASE WHEN key = 'MODEL' THEN value END) AS model
FROM forms_detailswhere
WHERE status = 'ACTIVE' AND key IN ('BRAND', 'MODEL')
GROUP BY form_id
) fdw ON fdw.form_id = f.id
WHERE f.status = 'ACTIVE'
ORDER BY f.id DESC;

Answer 2

You can PIVOT and then join:
SELECT cv.id,
cv.Ticket_id,
cv.serial_no,
cv.operator,
fd.computer_type,
fd.brand,
fd.model,
cv.status,
cv.datetime
FROM Form cv
LEFT OUTER JOIN (
SELECT *
FROM (
SELECT form_id, key, value
FROM Form_Details
WHERE status = 'ACTIVE'
)
PIVOT (
MAX(value)
FOR key IN (
'BRAND' AS brand,
'MODEL' AS model,
'COMPUTER_TYPE' AS computer_type
)
)
) fd
ON (cv.id = fd.form_id)
where cv.status = 'ACTIVE'
order by id desc;