App Store Year-over-Year Revenue by Category

SQL practice question · Hard · Analytics · Apple

Net revenue excludes refunded sales (`refunded` = 1). For each app category and calendar year with revenue, return `category`, `year` (integer), `revenue` (ROUND 2) and `yoy_pct` = ROUND(100.0 * (revenue - prev) / prev, 1), where prev is the same category's revenue in the immediately previous calendar year; NULL if that year has no revenue row. Order by `category`, `year`.

Table: apps

Schema of apps
ColumnType
app_idINTEGER
app_nameTEXT
categoryTEXT
Sample rows of apps
app_idapp_namecategory
1Pixel QuestGames
2Tile RushGames
3BeatLabMusic
4Fold NotesProductivity
5Snap EditPhoto

Table: app_sales

Schema of app_sales
ColumnType
sale_idINTEGER
app_idINTEGER
sale_dateDATE
amountREAL
refundedBOOLEAN
Sample rows of app_sales
sale_idapp_idsale_dateamountrefunded
112024-03-011000
222024-07-01500
312025-02-012000
422025-05-01801
512026-01-151800
632024-04-04400
732026-06-06600
Expected output on the sample data
categoryyearrevenueyoy_pct
Games2024150NULL
Games202520033.3
Games2026180-10
Music202440NULL
Music202660NULL

Solve it in the live editor on this page — run on sample data, then submit against hidden tests.

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