Calculate the percentage change with respect to the previous year, quarter and category - sql

Question

Using ORACLE SQL, I have a query that gives me the output in the following table(posting an image). However, I need to figure out a way to get the percentage change between year, quarter and metric in an additional column.
Example: Year 2022, Q1, apple against Year 2021, Q1, apple.
I'm relatively new to SQL so I'm not sure if I need to sort the output differently to use the function LEAD, or if there is a better way to do it in general.
My current query with my attempt at the percent change with lead (that didn't work) is like this:
`
SELECT s.YEAR
, t.quarter
, CASE WHEN fruits IN ('tangerine','lemon') THEN 'orange'
ELSE fruits
END metric
, COUNT(DISTINCT s.ID) AS COUNT
-- , ROUND((COUNT(UNIQUE s.ID) - LEAD(COUNT(UNIQUE s.ID)) OVER (ORDER BY t.quarter))/COUNT(UNIQUE s.ID)*100,2) pct_change
FROM s
JOIN sc
ON S.KEY = SC.KEY
JOIN c
ON SC.KEY = C.KEY
JOIN t
ON s.quarter = t.quarter
WHERE S.YEAR BETWEEN '2021' AND '2022'
AND s.quarter IN ('1','2','3')
GROUP BY S.YEAR
, t.quarter
,CASE WHEN fruits IN ('tangerine','lemon') THEN 'orange'
ELSE fruits
END
`

Answer 1

With my query as (
...your original query as above goes here...
)
Select curr.year, curr.quarter, curr.metric
, curr.count as current_count
, Case When prior.count is null then prior.count else if prior.count = 0 then null else (curr.count - prior.count)/ prior.count*100 as pct_chg
From my_query curr Left Outer Join my_query prior
On curr.year-1 = prior.year and
curr.qtr=prior.qtr and
curr.metric=prior.metric