Data analyst interviews test SQL skills, analytical thinking, and business communication. These questions cover the topics most frequently asked by hiring managers.
Multiple approaches: 1) SELECT MAX(salary) FROM employees WHERE salary < (SELECT MAX(salary) FROM employees). 2) Using DENSE_RANK(): WITH ranked AS (SELECT salary, DENSE_RANK() OVER (ORDER BY salary DESC) as rnk FROM employees) SELECT salary FROM ranked WHERE rnk = 2. Discuss trade-offs of each approach.
Systematic approach: 1) Check data correctness (tracking broken?). 2) Segment by source (organic, paid, referral). 3) Check for technical issues (site down, form broken). 4) Compare to external factors (competitor launch, seasonality). 5) Look at funnel metrics (visits stable but conversion dropped?). Present findings with data.
INNER JOIN returns only matching rows from both tables. LEFT JOIN returns all rows from the left table plus matching rows from the right (NULLs for non-matches). FULL OUTER JOIN returns all rows from both tables with NULLs where there is no match. Give a practical example of when to use each.
Key KPIs: conversion rate, average order value (AOV), customer acquisition cost (CAC), customer lifetime value (CLV), cart abandonment rate, repeat purchase rate. Set up dashboards in Tableau/Power BI with daily/weekly tracking. Establish baselines and set targets based on industry benchmarks.
Use STAR method. Describe the business question, your analysis approach, what the data revealed, and how stakeholders acted on your recommendation. Quantify the impact of the decision that was made based on your analysis.