Top 50 data cleaning Interview Questions
The most frequently asked data cleaning questions across all roles and companies, ranked by real interview frequency. Updated daily.
Replace missing sales fields with defined defaults and return a consistently ordered dataset.
University of Minnesota
The Home Depot
NationwideFilter invalid game events and normalize event names using PostgreSQL string and null handling.
Quantium
Scopely
CarvanaPrepare valid encounter records by trimming text, excluding missing values, and removing invalid charges.
Massachusetts General Hospital
Cognizant
DataVisorCreate an auditable application dataset by applying explicit PostgreSQL rules for missing candidate, status, salary, and date values.
Aircall
athenahealth
HaysIdentify duplicate transaction rows, retain the earliest record, and delete later duplicates safely.
Oracle
Amex
BrooksourceFind customer records with repeated non-empty email addresses, treating case and surrounding whitespace as insignificant.
Philips
PwCIdentify missing and invalid longitudinal measurements using scheduled visits and measurement validation rules.
Identify transactions with missing fields or store-level amount outliers using PostgreSQL data-quality logic.
Walmart de México y CentroaméricaSign up to see every question
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