BI Developer

01.1Resume

CoreBeginner3–5 h

A one-page resume you can defend line by line.

What this covers

• One-page format — Reverse-chronological, clean fonts, no photos or tables that confuse parsers.
• Project bullets — Action + what you built + a number (users, speed, accuracy).
• Skills section — Only skills you can answer questions on for two minutes.
• ATS readability — Export a text-based PDF and check it with a parser.
• Working links — GitHub, LinkedIn and a live project link that open.
• Tailoring — Reorder bullets to match the job description.

What to practise

• Run your PDF through a parser test
• Rewrite each bullet as action + result
• Remove any skill you can't explain for 2 minutes

Common questions

• Walk me through your resume.
• Which project here are you most proud of, and why?
• Why is this skill on your resume?

Free resources

• OpenResume — Free ATS-friendly resume builder and parser test (Free)
• Jake's Resume (Overleaf) — The LaTeX resume template most SDE freshers use (Free)
• Resume Worded — Resume and LinkedIn scoring (Free plan)
• Jobscan — Match your resume against a job description (Free plan)

Free courses

• Professional Resume Writing — Alison (Free course)
• Resume, Networking, and Interview Skills — Fullbridge (Free to audit)

01.2Tell me about yourself

CoreBeginner1–2 h

A 60–90 second answer: present, past, why this role.

What this covers

• Present — Who you are now: degree, year, focus.
• Past — One or two proof points: a project, internship or result.
• Future — Why this role and this company next.
• Length — 60–90 seconds; stop before you list everything.
• Delivery — Calm pace and eye contact, not a memorised script.

What to practise

• Write it, then say it out loud 5 times
• Record yourself and cut anything over 90 seconds

Common questions

• Tell me about yourself.
• Why should we hire you?
• Where do you see yourself in a few years?

Free resources

• Google Interview Warmup — Free spoken mock interview that prints your transcript (Free)
• BBC Learning English — Structured free English lessons and podcasts (Free)

Free courses

• English@Work: Basic Job Interview Skills — The Hong Kong Polytechnic University (Free to audit)
• Job Interview Preparation For Tech Professionals — University of Cape Town (Free to audit)

01.3Behavioral & STAR

CoreBeginner3–4 h

Stories about teamwork, conflict and failure, told with STAR.

What this covers

• STAR structure — Situation, task, action, result. Spend most of the time on action.
• Story bank — 6–8 real stories you can reuse across questions.
• Teamwork & conflict — Disagreeing respectfully and what you changed.
• Failure & weakness — A real one, what you learned, what you do now.
• Ownership — Times you took initiative without being asked.
• Common HR questions — Why us, why you, strengths, relocation.

What to practise

• Write 6 stories in STAR form
• Map each story to 2–3 common questions
• Practise one story with a friend

Common questions

• Tell me about a time you failed.
• Describe a conflict in a team and what you did.
• What is your biggest weakness?

Free resources

• Tech Interview Handbook — Free guide to coding and behavioral interviews (Free)
• Google Interview Warmup — Free spoken mock interview that prints your transcript (Free)
• Pramp / Exponent peer mocks — Free peer-to-peer mock interviews (Free plan)

Free courses

• Master Behavioral Interviews (for Software Engineers) — freeCodeCamp (Free video)
• Behavioral Interview Practice for Computer Science Students — CodeSignal (Free to audit)
• Soft Skills For Tech Professionals — University of Cape Town (Free to audit)

02.1DBMS

CoreIntermediate6–10 h

Keys, normalisation, transactions and writing SQL by hand.

What this covers

• Keys & constraints — Primary, foreign, candidate, unique.
• ER modelling — Entities, relationships, cardinality.
• Normalisation — 1NF to 3NF/BCNF and why it matters.
• Transactions & ACID — Atomicity, consistency, isolation, durability.
• Indexing — B-trees; when an index helps and when it hurts.
• SQL by hand — Joins, GROUP BY and subqueries on paper.

What to practise

• Write 15 SQL queries by hand
• Normalise one messy table on paper

Common questions

• What is normalisation and why does it matter?
• Primary key vs foreign key?
• What does ACID stand for?

Free resources

• GeeksforGeeks — Company-wise questions and theory (Free plan)
• SQLZoo — SQL by doing, in the browser (Free)
• InterviewBit — Guided interview prep path (Free plan)

Free courses

• Database Management System — Great Learning (Free course)
• Database Systems - Cornell University Course (SQL, NoSQL, Large-Scale Data Analysis) — freeCodeCamp (Free video)
• Database Systems — MIT OpenCourseWare (Free course)

02.2SQL for analytics

CoreIntermediate10–15 h

Business questions answered in SQL, from joins to window functions.

What this covers

• Joins & filters — Inner, left, anti-joins and their traps.
• Aggregation — GROUP BY, HAVING, conditional sums.
• Window functions — RANK, LAG, running totals, moving averages.
• CTEs & subqueries — Breaking hard questions into steps.
• Dates — Grouping by week or month, cohorts.
• NULLs & duplicates — Handling messy data correctly.

What to practise

• Solve 30 interview-style SQL questions
• Write a monthly retention query from scratch

Common questions

• Find the second-highest salary per department.
• Calculate 7-day rolling average sales.
• Difference between WHERE and HAVING?

Free resources

• Mode SQL tutorial — SQL for analysis, from basics to window functions (Free)
• DataLemur — SQL and analytics interview questions (Free plan)
• StrataScratch — Real SQL and Python data interview questions (Free plan)
• SQLZoo — SQL by doing, in the browser (Free)

Free courses

• SQL and Relational Databases 101 — IBM (Free course)
• CS50's Introduction to Databases with SQL — Harvard University (Free video)

03.1Data warehousing & modelling

CoreIntermediate6–10 h

Modelling data for analytics: facts, dimensions and warehouses.

What this covers

• Star schema — Facts, dimensions, grain.
• Slowly changing dimensions — Keeping history correctly.
• Warehouses — BigQuery, Snowflake, Redshift concepts.
• Performance — Partitioning and clustering.
• Semantic layer — Consistent metric definitions.

What to practise

• Design a star schema for an online store
• Write the SQL that loads one dimension

Common questions

• What is a star schema?
• What is the grain of a fact table?

Free resources

• Google Cloud Skills Boost — Labs and paths for GCP and AI (Free plan)
• Mode SQL tutorial — SQL for analysis, from basics to window functions (Free)
• Use The Index, Luke — SQL indexing and performance, free online (Free)

Free courses

• Data Warehouse & Data Mining — Gate Smashers (Free video)
• Modern Data Warehousing with ETL Processes — Great Learning (Free course)
• Modernizing Data Lakes and Data Warehouses with Google Cloud — Google Cloud (Free to audit)

03.2Data visualisation & dashboards

CoreIntermediate6–10 h

Choosing the right chart and building dashboards people use.

What this covers

• Chart choice — Bars, lines, scatter and when each works.
• Dashboard design — Key numbers first, filters, clear titles.
• A BI tool deeply — Power BI or Tableau: models, measures, filters.
• Storytelling — Insight, evidence, recommendation.
• Avoiding misleading charts — Axes, scales and colour.

What to practise

• Build and publish one dashboard on a public dataset
• Turn one chart into a 3-sentence insight

Common questions

• How would you design a sales dashboard?
• When is a pie chart a bad idea?

Free resources

• Tableau Public — Free Tableau to build and publish dashboards (Free)
• Power BI on Microsoft Learn — Free Power BI learning paths (Free)
• Excel Easy — Free Excel tutorial from basics to pivot tables (Free)

Free courses

• Data Visualization with Python — IBM (Free course)
• Data Visualization with R — IBM (Free course)
• Data Visualization — Kaggle (Free course)

04.1Data cleaning & wrangling

CoreIntermediate6–10 h

Getting messy data ready, the part of the job that takes most time.

What this covers

• Missing values — Drop, fill or flag, and why.
• Outliers — Spotting them and deciding what to do.
• Types & formats — Dates, currencies, categories.
• Joining datasets — Keys, duplicates, row explosions.
• Reproducibility — Scripted steps instead of manual edits.

What to practise

• Clean a messy public dataset and document every step
• Find three data-quality issues in a sample file

Common questions

• How do you handle missing values?
• How would you check a dataset is correct?

Free resources

• Kaggle Learn — Short practical courses: Python, Pandas, ML, SQL (Free)
• Excel Easy — Free Excel tutorial from basics to pivot tables (Free)
• StrataScratch — Real SQL and Python data interview questions (Free plan)

Free courses

• Data Cleaning — Kaggle (Free course)
• Sensor Data Cleaning: Filter Techniques — Alison (Free course)
• Basics of Python Data Wrangling — Great Learning (Free course)

04.2Business metrics

CoreIntermediate4–8 h

KPIs, funnels and retention: the language of analytics interviews.

What this covers

• KPIs — Revenue, conversion, active users, churn.
• Funnels — Step-by-step conversion and drop-offs.
• Retention & cohorts — Who comes back and when.
• Unit economics — CAC, LTV, margins.
• North-star metrics — One metric that reflects value delivered.

What to practise

• Define 5 KPIs for an app you use
• Build a cohort retention table from sample data

Common questions

• What metrics would you track for a food delivery app?
• Daily active users dropped 10%. What do you check?

Free resources

• Exponent — Product, data and engineering interview questions and guides (Free plan)
• StrataScratch — Real SQL and Python data interview questions (Free plan)
• Mode SQL tutorial — SQL for analysis, from basics to window functions (Free)

Free courses

• Mastering 11 Essential Business KPIs — Alison (Free course)
• Top Five KPIs for Small Businesses — Alison (Free course)

04.3Projects & resume defense

CoreIntermediate4–6 h

Explaining what you built, why, and what you would change.

What this covers

• The problem — What it solves and for whom.
• Your role — Exactly what you built yourself.
• Architecture — A simple diagram: frontend, backend, database.
• Hardest bug — What broke and how you found it.
• Trade-offs — Why this stack; what you would change now.
• Scale questions — What happens with 10x the users.

What to practise

• Prepare a 2-minute walkthrough per project
• Be ready to draw its architecture

Common questions

• What was the hardest part of this project?
• Why did you choose this tech stack?
• How would it handle 10x more users?

Free resources

• Tech Interview Handbook — Free guide to coding and behavioral interviews (Free)
• Pramp / Exponent peer mocks — Free peer-to-peer mock interviews (Free plan)

Free courses

• Software Engineering Concepts — MIT OpenCourseWare (Free course)
• Build community-driven software projects on GitHub — Microsoft (Free course)

05.1Technical mock interviews

CoreIntermediate3–6 h

At least two full coding mocks before the real one.

What this covers

• Thinking aloud — Narrate your approach before and while coding.
• Clarifying questions — Confirm inputs, scale and edge cases first.
• Handling hints — Take them gracefully and adapt.
• "I don't know" — Say what you do know and how you would find out.
• Review the recording — Fillers, pace, unclear explanations.

What to practise

• Do two peer mock interviews
• Record one spoken mock and listen back

Common questions

• Walk me through your approach before you code.
• How would you test this?

Free resources

• Pramp / Exponent peer mocks — Free peer-to-peer mock interviews (Free plan)
• Google Interview Warmup — Free spoken mock interview that prints your transcript (Free)
• Tech Interview Handbook — Free guide to coding and behavioral interviews (Free)

Free courses

• Software Engineering Job Interview – Full Mock Interview — freeCodeCamp (Free video)

06.1Company research

CoreBeginner1–2 h

The product, the role, the job description and recent news.

What this covers

• The business — What it sells and to whom.
• The role — What the job description really asks for.
• Recent news — Launches, results, announcements.
• Interview format — The rounds, if the company shares them.
• Your fit — Three reasons, matched to the job description.

What to practise

• Write 3 reasons you want this role
• Match 3 JD lines to your experience

Common questions

• Why do you want to work here?
• What do you know about our product?

Free resources

• GeeksforGeeks — Company-wise questions and theory (Free plan)
• Tech Interview Handbook — Free guide to coding and behavioral interviews (Free)

06.3Final checklist

CoreBeginner30 min

Logistics, documents, setup and a calm night before.

What this covers

• Logistics — Time, timezone, link or address.
• Documents — Resume copies, ID, certificates if asked.
• Tech check — Camera, mic, internet, charger.
• Night before — Sleep, light revision, no new topics.

What to practise

• Do a 5-minute tech check the day before
• Lay out documents and clothes the night before

Free resources

• Google Interview Warmup — Free spoken mock interview that prints your transcript (Free)