Unpivot Columns to Rows — Solution & ExplanationProblems / Unpivot Columns to Rows / EditorialApproachThis is the inverse of pivoting — converting columns back into rows (also called unpivot or melt).UNION ALL ApproachWrite one SELECT per column you want to unpivot, each producing:

The identifier columns (here product_name) unchanged

A string literal for the new label column ('Q1', 'Q2', etc.)

The value column renamed to a common alias (sales_amount)

Then UNION ALL the results together.Why This WorksEach SELECT reads the same table but extracts a different column. UNION ALL stacks them vertically. The result is N × M rows where N is the original row count and M is the number of unpivoted columns.DuckDB AlternativeDuckDB supports UNPIVOT syntax natively:```sqlUNPIVOT quarterly_resultsON q1_sales, q2_sales, q3_sales, q4_salesINTO NAME quarter VALUE sales_amount```But UNION ALL is more portable across SQL dialects.Hints

UNION ALL combines multiple SELECT statements row-wise. Each SELECT extracts one column into the normalized format.

Use F.lit() to create a constant column value like the quarter label.

DuckDB also supports UNPIVOT syntax as a shortcut, but UNION ALL is the portable approach.

Solve Unpivot Columns to Rows yourself →