Data & Analytics•SOTAAZ Lab•December 3, 2025•KR

One Wrong JOIN and Your Revenue Doubles — The Complete Guide to Accurate Revenue Aggregation

Row Explosion in 1:N JOINs and how to aggregate revenue correctly

One Wrong JOIN and Your Revenue Doubles — The Complete Guide to Accurate Revenue Aggregation

Pivot Table 30 Min vs SQL 30 Sec, But Why Don't the Numbers Match?

"Huh, that's weird. Why is revenue so high?"

Ever discovered your revenue numbers are 2x off from the finance team's report right before presenting? This problem—caused by JOIN results inflating due to 1:N relationships—happens to almost every analyst at least once.

This guide doesn't just show query patterns. We'll deeply cover how to diagnose why revenue gets inflated and techniques for accurate aggregation without duplicates.

1. The Problem: Why Is My Query Result 2x Off?

You're trying to calculate monthly revenue from order data:

sql

SELECT
    strftime('%Y-%m', o.order_date) as month,
    SUM(o.total_amount) as revenue
FROM orders o
JOIN order_items oi ON o.order_id = oi.order_id
GROUP BY strftime('%Y-%m', o.order_date);

Result:

month	revenue
2024-01	156,234,000
2024-02	178,456,000

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One Wrong JOIN and Your Revenue Doubles — The Complete Guide to Accurate Revenue Aggregation

Pivot Table 30 Min vs SQL 30 Sec, But Why Don't the Numbers Match?

The rest of this series is paid

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