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Interview preparation roadmap · Technology

Schema design, advanced SQL and performance, plus coding rounds in some companies.

SQLModellingPerformance

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  1. 01Interview foundations
  2. 02Coding
  3. 03Database foundations
  4. 04Role-specific
  5. 05Practice
  6. 06Company & final prep
CoreCommonly assessedGood to knowRole-dependentAdvancedFor deeper interviewsOptionalNot needed by everyoneCompletedYour progressYou are hereNext up
  1. 01Interview foundations

    What every interviewer sees first.

    1. 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

    2. 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

      Free courses

    3. 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

      Free courses

  2. 02Coding

    Common in product companies.

    1. 02.1Programming fundamentals

      CoreBeginner6–10 h

      One language you know well: syntax, memory, complexity.

      What this covers

      • One language deeply — C++, Java or Python: syntax, standard library, quirks.
      • Time & space complexity — Big-O of loops, recursion and common operations.
      • Recursion — Base cases, the call stack, when it overflows.
      • Memory basics — Stack vs heap, references vs values, garbage collection.
      • Strings & arrays — Immutability, copying and slicing costs in your language.
      • Debugging — Reading errors, dry runs, using a debugger.

      What to practise

      • Solve 10 easy problems without an IDE's help
      • Explain the complexity of each solution aloud

      Common questions

      • What is the time complexity of your solution?
      • What happens in memory when you call a function?
      • Difference between an array and a linked list?

      Free resources

      Free courses

    2. 02.2Data structures & algorithms

      Good to knowIntermediate40–80 h

      The core problem-solving topics commonly assessed in software interviews.

      What this covers

      • Arrays & hashing — Frequency maps, prefix sums, duplicates.
      • Two pointers & sliding window — Pairs, subarrays and substrings in O(n).
      • Stacks & queues — Brackets, monotonic stacks, BFS queues.
      • Linked lists — Reversal, cycle detection, merging.
      • Trees & BST — Traversals, height, LCA, validation.
      • Graphs — BFS, DFS, topological sort, shortest paths.
      • Binary search — On sorted arrays and on the answer.
      • Dynamic programming — 1D and 2D DP, from climbing stairs to knapsack.

      What to practise

      • Follow one list end to end, not five
      • Say the brute force first, then improve it
      • One timed problem a day

      Common questions

      • What is the difference between BFS and DFS?
      • How does a hash map handle collisions?
      • Find the first non-repeating character in a string.

      Free resources

      Free courses

  3. 03Database foundations

    The main rounds.

    1. 03.1DBMS

      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

    2. 03.2SQL for interviews

      Good to knowBeginner4–6 h

      Query questions that show up in many tech and data rounds.

      What this covers

      • SELECT basics — Filtering, sorting, LIMIT.
      • Joins — Inner, left and self joins.
      • Aggregation — GROUP BY, HAVING, COUNT DISTINCT.
      • Subqueries & CTEs — Breaking a hard query into steps.
      • Window functions — RANK, ROW_NUMBER, running totals.

      What to practise

      • 20 interview-style SQL questions
      • Rewrite one long query using a CTE

      Common questions

      • Find the second-highest salary.
      • INNER JOIN vs LEFT JOIN?

      Free resources

      • SQLZoo — SQL by doing, in the browser (Free)
      • DataLemur — SQL and analytics interview questions (Free plan)

      Free courses

    3. 03.3Databases in depth

      CoreAdvanced8–12 h

      Performance, transactions and operations for database roles.

      What this covers

      • Query plans — Reading EXPLAIN and fixing slow queries.
      • Indexing strategy — Composite, covering and partial indexes.
      • Isolation levels — Read phenomena and locking.
      • Replication & HA — Primary/replica, failover.
      • Backup & recovery — Point-in-time recovery, testing restores.
      • Security — Roles, privileges, auditing.

      What to practise

      • Speed up a slow query using an index and EXPLAIN
      • Set up a replica locally

      Common questions

      • What are isolation levels?
      • How would you find a slow query in production?

      Free resources

      Free courses

  4. 04Role-specific

    Design at scale.

    1. 04.1Data warehousing & modelling

      Good to knowIntermediate6–10 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

      Free courses

    2. 04.2System design basics

      Good to knowAdvanced10–20 h

      More common for experienced roles; some fresher rounds touch it.

      What this covers

      • Client–server basics — Requests, APIs, stateless servers.
      • Load balancing — Spreading traffic across servers.
      • Caching — What to cache, where, and invalidation.
      • Databases at scale — SQL vs NoSQL, replication, sharding.
      • Queues — Async work and decoupling.
      • Classic problems — URL shortener, chat, news feed.

      What to practise

      • Design a URL shortener on paper
      • Explain trade-offs, not just boxes

      Common questions

      • Design a URL shortener.
      • How would you scale a read-heavy app?

      Free resources

      Free courses

    3. 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

      Free courses

  5. 05Practice

    Saying it out loud is a different skill.

    1. 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

      Free courses

    2. 05.2Technical communication

      Good to knowBeginner2–3 h

      Explaining your thinking clearly in English.

      What this covers

      • Structure — Big picture first, then details.
      • Plain words — Explain without jargon.
      • Checking in — "Does that make sense so far?"
      • Written English — Clear emails and follow-ups.

      What to practise

      • Explain one project to a non-CS friend
      • Record a 2-minute explanation of your best project and listen back

      Common questions

      • Explain recursion to a 10-year-old.

      Free resources

      Free courses

  6. 06Company & final prep

    The last 48 hours.

    1. 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

    2. 06.2Questions to ask

      Good to knowBeginner30 min

      Two or three good questions for the end of the interview.

      What this covers

      • About the team — How work is planned and reviewed.
      • About growth — Mentoring, learning, the first 90 days.
      • About the product — What is hard right now.
      • What to avoid — Questions a quick search answers.

      What to practise

      • Write 5 questions, keep the best 3
      • Prepare one question about the team's own product

      Common questions

      • Do you have any questions for us?

      Free resources

    3. 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

    4. 06.4Job & interview safety

      Good to knowBeginner15 min

      Spot fake offers, payment requests and fake interview links.

      What this covers

      • Payment requests — Real employers don't charge for jobs or training.
      • Email domains — Check it matches the company's own site.
      • OTPs & logins — Never share them with anyone.
      • Fake interview links — Care with unknown chat apps and downloads.
      • Reporting — The 1930 helpline and cybercrime.gov.in.

      What to practise

      • Check one recent offer against these rules
      • Confirm the opening is listed on the company's own careers page

      Free resources

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