Weekly Trends — Solution & ExplanationProblems / Weekly Trends / EditorialApproach

Truncate to week: Use DATE_TRUNC('week', sale_date) to get the Monday of each week.

Aggregate: Sum revenue per week and round to 2 decimal places.

Previous week: Use LAG(weekly_revenue) OVER (ORDER BY week_start) to get the prior week's total.

Compute change: Calculate (current - previous) / previous * 100 for the percentage change.

Filter: Exclude the first week where there's no comparison baseline.

Key ConceptCombining DATE_TRUNC for time bucketing with LAG for period-over-period comparison is one of the most common patterns in time series analytics.Hints

DATE_TRUNC('week', date) returns the Monday of each week.

Use LAG() to access the previous week's revenue after aggregating weekly totals.

The WoW change formula is (current - previous) / previous * 100.

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