What does LAG(value, 1, 0) return when there is no previous row in the partition?

Problem Statement

Explanation

LAG reads a value from a previous row in the same ordered partition. When that row does not exist, the default is used. Supplying a safe default keeps arithmetic stable and avoids NULL propagation in first-row calculations.

Code Solution

SolutionRead Only

SELECT day, amount,
       LAG(amount, 1, 0) OVER (PARTITION BY product ORDER BY day) AS prev_amt
FROM daily_sales;

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What does LAG(value, 1, 0) return when there is no previous row in the partition?

Problem Statement

Explanation

Code Solution

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What does LAG(value, 1, 0) return when there is no previous row in the partition?

Problem Statement

Explanation

Code Solution

Practice Sets

Related Questions

Which SQL statement retrieves all columns and rows from a table named employees?

Which clause filters rows before aggregation and affects which rows are grouped?

What is the default sort order when ORDER BY is used without ASC or DESC?

Which construct is commonly used to paginate results in SQL engines like Postgres and MySQL?

Which predicate correctly checks for missing values in standard SQL?

More from SQL & Databases

Master Interviews
Anywhere, Anytime