
Dan Patiño
AI Strategy & Innovation at Coderhouse
Data
Data Analyst Interview Questions: SQL, Excel, and Case Study Rounds Explained
Data analyst interview questions usually fall into five groups: SQL, spreadsheets, statistics and metrics, visualization or BI tools, and a business case study, plus behavioral questions about how you work with people. Entry-level interviews rarely test obscure syntax. They test whether you can take a vague business question, get the right data, check that it is correct, and explain what someone should do next.
Why it matters: career changers often over-prepare for trivia and under-prepare for the case round, which is where many hiring decisions are made. Knowing what each round is scoring lets you spend your prep time where it counts.
How a typical data analyst interview process works
Formats vary by company, but a common sequence looks like this:
Recruiter screen: background, motivation, salary expectations, and logistics.
Technical screen: live SQL or a short take-home exercise.
Case study or take-home analysis: a dataset and a business question, followed by a presentation.
Team and behavioral interviews: collaboration, communication, and how you handle ambiguity.
Round 1: SQL questions
SQL is the most consistently tested skill for analyst roles. Expect questions like:
“Find the top five products by revenue last month.” (aggregation, filtering, sorting)
“List customers who placed an order but never returned for a second one.” (joins, subqueries, or
NOT EXISTS)“Calculate a running total of daily sign-ups.” (window functions)
“Rank sales reps within each region.” (
RANK()orROW_NUMBER()withPARTITION BY)“What is the difference between
WHEREandHAVING?” or “betweenINNERandLEFT JOIN?”
What they are scoring: correct logic, handling of NULLs and duplicates, and whether you talk through assumptions out loud. If window functions feel shaky, the PostgreSQL window functions tutorial is a clear reference. Our list of common SQL mistakes for data analysts covers the errors interviewers notice most.
Round 2: Spreadsheet questions
Many teams still run on Excel or Google Sheets, so expect practical tasks:
Build a pivot table that summarizes sales by region and month.
Use
XLOOKUPorINDEX/MATCHto combine two tables.Clean a column with inconsistent dates or text values.
Explain when you would move from a spreadsheet to SQL or Python.
What they are scoring: speed, tidy structure, and whether someone else could understand your file.
Round 3: Statistics and metrics questions
You do not need advanced math, but you do need sound judgment:
“When would you use the median instead of the mean?”
“Conversion dropped 8% this week. How would you investigate?”
“Explain an A/B test to a non-technical manager.”
“What is the difference between correlation and causation? Give an example.”
“How would you define an ‘active user’ for this product?”
What they are scoring: structured thinking. For metric drops, a strong answer checks data quality first, then segments the change (by platform, region, channel, new versus returning users), then looks for external causes such as releases or seasonality.
Round 4: Visualization and BI questions
“Walk me through a dashboard you built. Who used it, and what decision did it support?”
“Which chart would you use to show change over time? Composition? Distribution?”
“How would you handle a stakeholder who wants twenty metrics on one screen?”
Power BI and Tableau are the most common tools in job postings; Microsoft’s free Power BI training is a good way to fill gaps. For design guidance, see our dashboard design principles.
Round 5: The case study
A case study gives you a dataset or scenario, such as “Our subscription churn is rising; what should we do?”, and asks you to analyze and present. A reliable structure:
Clarify the goal: which decision will this analysis inform, and how is success measured?
State assumptions and check the data for gaps, duplicates, and odd values.
Analyze in layers: overall trend first, then segments, then likely drivers.
Recommend: one to three actions, the expected impact, and what you would test next.
Name the limits of your analysis honestly.
Interviewers care more about the recommendation and reasoning than about fancy charts. Projects like the ones in our guide to SQL portfolio projects double as case-study practice.
Behavioral questions
“Tell me about a time your analysis changed a decision.”
“Describe a time you found an error in the data. What did you do?”
“How do you explain technical results to non-technical people?”
Answer with the STAR format (situation, task, action, result) and include a number whenever you can. Career changers should draw on past jobs: a retail manager who tracked inventory or a marketer who reported campaign results already has relevant stories.
A two-week prep plan
Days 1–5: one SQL problem set per day, focusing on joins, aggregations, and window functions.
Days 6–8: spreadsheet drills and two metric-investigation questions answered out loud.
Days 9–11: one full case study with a five-slide presentation.
Days 12–14: write six STAR stories and do a mock interview with a friend.
FAQ
How hard are entry-level data analyst interviews?
The SQL is usually intermediate rather than advanced. The harder part is clear thinking and communication under time pressure.
Will they ask Python questions?
Increasingly, yes, mostly basic pandas work such as filtering, grouping, and merging. SQL still tends to carry more weight.
What if I freeze on a live SQL question?
Say your plan out loud, write a simpler version first, and then refine it. Interviewers often reward a clear process over a perfect first answer.
Coderhouse’s Data Analytics course is built for career switchers and analysts. It runs for eleven weeks with one live class per week and about 6–8 hours of work weekly, covering SQL, Python, visualization, statistics, experimentation, and AI-assisted analytics, and it closes with a capstone and career-readiness week. You can try two classes free. Explore these Coderhouse courses:
Data Analytics Course — practice the SQL, statistics, and case-study skills interviewers test, with live feedback.
AI Engineering Course — for developers who want to build LLM applications on top of data skills.
I'm Dan Patiño, head of AI Strategy & Innovation at Coderhouse. My day-to-day work involves merging the tactical management of e-commerce (CRO, Email Marketing and SEO) with the development of disruptive solutions. I specialize in building internal AI-powered apps to automate tasks and boost innovation within the team. I firmly believe that technology is strategy's best ally. To dive deeper into my professional journey, I'll be waiting for you on my LinkedIn profile.