Dataford
Interview QuestionsInterview GuidesExperiencesMock InterviewsPricing
Get started
Dataford
Popular roles
Software EngineerData AnalystData ScientistData EngineerBusiness AnalystAI EngineerMachine Learning EngineerProduct Manager
Browse
Browse All RolesEvery role hub, from analyst to MLBrowse All CompaniesCompany-specific interview loopsAll Interview GuidesThe full guide library
Top questions by role
Software EngineerData AnalystData ScientistData EngineerBusiness AnalystAI EngineerMachine Learning EngineerProduct Manager
Top questions by skill
SQLPythonStatisticsMachine LearningA/B TestingSystem DesignGenerative AIProduct SenseMetricsBehavioral
Browse all questions →Try a mock interview
Experiences
Practice
Mock InterviewsTimed interview simulations with feedbackSuccess PathYour 6-week structured planModulesCurated lessons by topicWebinarsTalks from ex-Big Tech data leadsPlaygroundA free-form scratch editor
Learn
BlogInterview strategy and career adviceTech Job Market ReportHiring trends across data and AI rolesFor UniversitiesDataford for career centersAbout DatafordWho we are and how we build
Pricing
Build my plan
Analyzing Data in SQL
00:00
5 left

Analyzing Data in SQL

MediumSQL · PostgreSQL

Problem

Tell me about a time you had limited time to review data and then used SQL to analyze it and reach a conclusion.

For this exercise, use the supplied account and transaction data to produce a concise review conclusion for the specified seven-day period.

Output

  1. One row per account, including accounts with no qualifying transactions
  2. Columns: account_name, transaction_count, failed_count, failure_rate_pct, and review_conclusion
  3. Classify an account as REVIEW when it has at least two transactions and at least 50% failed transactions, NO_ACTIVITY when it has none, and NO_REVIEW otherwise
  4. Sort by account_id ascending

Schema

accounts
ColumnTypeDescription
account_idPKINTUnique account identifier
account_nameVARCHAR(100)Account display name
transactions
ColumnTypeDescription
transaction_idPKINTUnique transaction identifier
account_idINTAccount associated with the transaction
occurred_atDATETransaction date
statusVARCHAR(20)Transaction outcome
amountDECIMAL(10,2)Transaction amount
Tablesaccountstransactions
Interviewer

Your question is Analyzing Data in SQL. Start with the requirements and the two tables in the Question tab.

Run and submit as often as you like. When you're ready, talk me through your approach or go straight to the code.

You need to log in / sign up to run or submit.
CodePostgreSQL
Sign up free to run your codeLog inLn 1
Run your query to see results here.