Percentage of Total — Solution & ExplanationProblems / Percentage of Total / EditorialApproach

GROUP BY department and compute SUM(amount) for each.

Divide each department's total by the grand total (sum of all sales) and multiply by 100.

ROUND to 2 decimal places.

SQL TechniqueA scalar subquery (SELECT SUM(amount) FROM sales) computes the grand total once and makes it available to every row.PySpark TechniqueCompute the grand total as a one-row DataFrame, then crossJoin it so every grouped row can reference it.Hints

Use a scalar subquery (SELECT SUM(amount) FROM sales) to get the grand total in SQL.

In PySpark, compute the grand total as a separate single-row DataFrame and crossJoin it.

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