Tuesday, 22 July 2025

SQL - SQL Server interview questions

 1.⁠ ⁠Find the second highest salary per department using DENSE_RANK.

2.⁠ ⁠Get daily login count trend for the past 15 days.
3.⁠ ⁠Calculate user engagement duration using login/logout timestamps.
4.⁠ ⁠Identify duplicate transactions based on multiple columns.
5.⁠ ⁠Join user and transaction tables while handling NULLs correctly.
6.⁠ ⁠Retrieve top 5 products by revenue in the last 30 days.
7.⁠ ⁠Compute revenue delta between this month and last month.
8.⁠ ⁠Group data by week and count number of active users.
9.⁠ ⁠Perform LEFT JOIN with conditionally filtered rows.
10.⁠ ⁠Use CASE WHEN logic for tiering customers by total spend.
11.⁠ ⁠Check if transaction timestamps are in chronological order.
12.⁠ ⁠Handle missing values using COALESCE or default substitutions.
13.⁠ ⁠Track users with consecutive failed login attempts.
14.⁠ ⁠Find latest status per user using ROW_NUMBER partitioned by user ID.
15.⁠ ⁠Identify products with zero sales in the current quarter.
16.⁠ ⁠Join tables with SCD Type 1 dimension logic.
17.⁠ ⁠Apply HAVING clause to filter aggregate conditions.
18.⁠ ⁠Calculate average basket size per user per week.
19.⁠ ⁠Group and pivot sales data to display region-wise monthly totals.
20.⁠ ⁠Use Common Table Expressions (CTEs) to break complex logic into steps.

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