LAG

How can we access the previous order amount in chronological order?

Advanced⏱ 3 Minutes⭐ 1580 XP

🤔 THE QUESTION

How can we access the previous order amount in chronological order?

💡 WHAT IS IT?

LAG(column) accesses the value from the preceding row within the window without a self-join.

🎯 WHAT IS IT USED FOR?

Period-over-period delta calculation, day-over-day growth tracking, churn detection.

💻 EXAMPLE

SELECT
order_date,
amount,
LAG(amount) OVER (ORDER BY order_date) AS previous_amount
FROM orders;

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