Dataford
Interview QuestionsInterview GuidesExperiencesCoaching
New
Pricing
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 feedbackCoaching1:1 coaching with people at your target companiesSuccess 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
Odd-Total ID Swap Logic
00:00
5 left

Odd-Total ID Swap Logic

MediumSQL · PostgreSQL

Problem

If the total amount is an odd number, how would you swap the id for each two consecutive records and leave the last one unswapped?

Use the records table and return one row per record. Preserve the original row count, and if there is an unpaired final record, keep its id unchanged.

Output

  1. id as the swapped id value for each row
  2. value as the original row value
  3. Return rows ordered by the original record sequence

Schema

records
ColumnTypeDescription
idPKINTUnique record identifier
valueVARCHAR(100)Associated record value
Tablesrecords
Interviewer

Your question is Odd-Total ID Swap Logic. Start with the requirements and the one table 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.