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#0353
Unpivot Quarter Sales
MediumSQL24 min20 XP
Problem
Return product, quarter, and revenue from q1 and q2 columns.
Why This Matters
SQL interviews usually test whether you can turn a business question into the right rows, grouping level, join type, and edge-case behavior.
Schema
sales(product TEXT, q1 INTEGER, q2 INTEGER)
Examples
Example 1
Inputq1 and q2 columns
Outputtwo rows per product
UNION ALL stacks each quarter column into a row format.
Constraints
- Return only the requested columns.
- Use deterministic ORDER BY when multiple rows are returned.
- Assume SQLite-compatible SQL unless the prompt states otherwise.
CodeSQL
Visible browser tests run here when available.
Testcases1 visible / 3 hidden categories
Core SQL case
Inputq1 and q2 columns
Expected[["Book","q1",10],["Book","q2",15],["Pen","q1",5],["Pen","q2",7]]
UNION ALL stacks each quarter column into a row format.
Hidden Test Categories
Empty or missing matchesDuplicate rows or tiesNULL values where the pattern commonly breaks