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Top 50 null values Interview Questions

The most frequently asked null values questions across all roles and companies, ranked by real interview frequency. Updated daily.

50questions
~17htotal time
105companies covered
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1
JoinsStart here. 18 questions · ~360 min
Inner Join vs Outer JoinEasy
Practice
Recently asked

Demonstrate how INNER JOIN and FULL OUTER JOIN handle matching and unmatched rows.

JoinsData Wranglingnull valuesRocketNeenOpaleBay
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2
Date Functions3 questions · ~60 min
Rolling Average Over Last 30 DaysMedium
Practice
Recently asked

Calculate each customer's 30-day rolling engagement average using a PostgreSQL window function.

Date FunctionsData ManipulationAggregationsTTecholutionSSignifyEEleos Health
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3
Data Manipulation3 questions · ~60 min
Fourth Highest Salary in SQLMedium
Practice
Recently asked

Identify every employee earning the fourth-highest distinct non-NULL salary using PostgreSQL ranking.

Data Manipulationsqldatabase queryingBlackRockExpedia GroupMSCI
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4
Group By3 questions · ~60 min
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5
Window Functions3 questions · ~60 min
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6
More topics20 questions · ~400 min
Second Highest Value SQLEasy
Practice

Use a scalar subquery and MAX to find the second distinct annual salary.

sql queryRankingdatabase queryingLLuxoft SingaporePCS Global TechAmazon Web Services
Find the Second Highest SalaryMedium
Practice

Find the second highest distinct salary from an employee table, handling duplicate and NULL salary values.

database queryingAggregationsnull valuesAmazon Web ServicesNiCE
SQL: Second and Nth Highest SalaryMedium
Practice
Recently asked

Return employees tied at the second and fourth highest non-null salary levels using salary ranking.

sqldatabase queryingAggregationsNCR AtleosHashedIn by Deloitte
Second Largest SQL ValueEasy
Practice

Return the second largest distinct non-null value from a PostgreSQL table.

database queryingAggregationsnull valuesIInnova SolutionsSigmoid
Schema Risks and TradeoffsHard
Practice
Recently asked

Identify transaction data risks caused by nullable relationships, invalid amounts, inactive accounts, missing currencies, and duplicate references.

schema designdata integritynull valuesMercury
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