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Test SQL skills using advanced window functions such as LAG, LEAD, and DENSE_RANK.

SQLmedium0.7 min readPremium
Frequency
Low
Asked at 1 company
Category
487
questions in SQL
Difficulty Split
130E|271M|86H
in this category
Total Bank
1,863
across 7 categories
Asked at these companies
Carelon
Key Concepts Tested
partitionsqlwindow
Expert AnswerPremium
141 wordsInterview-ready
LAG, LEAD, and DENSE_RANK are powerful window functions. LAG(column, n) returns the value n rows before the current row; LEAD does the opposite. DENSE_RANK assigns ranks with no gaps for ties. Example—period-over-period comparison: SELECT date, revenue, LAG(revenue, 1) OVER (ORDER BY date) AS prev_revenue, revenue - LAG(revenue, 1) OVER (ORDER BY date) AS growth FROM sales; For ranking within partitions: SELECT employee_id, department_id, salary, DENSE_RANK() OVER (PARTITION BY department_id ORD...
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