SQL HAVING Clause Interview Questions
HAVING questions test your ability to filter aggregated data, a critical skill that goes beyond basic GROUP BY.
Expect questions combining GROUP BY, aggregates (SUM, COUNT, AVG), and HAVING conditions.
Interviewers evaluate whether you understand the difference between WHERE and HAVING, and proper ordering of clauses.
Common SQL HAVING interview patterns
- Filtering groups with HAVING vs filtering rows with WHERE
- HAVING with COUNT, SUM, AVG, and other aggregates
- TOP N per group using HAVING with aggregates
- Multiple conditions in HAVING clauses
- HAVING with complex aggregate expressions
- Combining GROUP BY, WHERE, and HAVING in the correct order
SQL HAVING clause interview questions
Compute time-spent percentage by app category
Find the most-used app
Solve three SQL problems (easy/medium/hard)
Count words in a document robustly
Fetch and parse JSON from REST API
Write SQL for library analytics
Transform flat keys into nested dictionary
Find users with multi-country successful logins
Parse CSV and format transactions
Fetch and aggregate paginated team data via API
Count sports by calendar quarter in SQL
Compute nearest index within threshold after walking distances
Implement vectorized NumPy ops and explain broadcasting
Manipulate time-series with Pandas groupby
Implement a Python test harness
Compute courier pay with peak-hour rules
Calculate minutes between two time strings
Perform EDA and diagnose data quality
Implement filtered transactions with cursor pagination
Common mistakes with HAVING
- Using WHERE instead of HAVING to filter aggregates
- Incorrect clause ordering (HAVING before GROUP BY)
- Aggregating already-aggregated values in HAVING
- Confusion between row-level filters (WHERE) and group-level filters (HAVING)
- Not considering NULL values in aggregate conditions
How HAVING questions are evaluated in interviews
Understanding the execution order of clauses is key.
Explain why WHERE filters rows but HAVING filters groups.
Demonstrate correct aggregate function usage in filtering contexts.
Related SQL concepts
SQL HAVING Clause Interview FAQs
What is the difference between WHERE and HAVING?
WHERE filters individual rows before aggregation occurs. HAVING filters groups after aggregation. You use WHERE to exclude rows from being aggregated, and HAVING to exclude groups from the final result.
Can you use HAVING without GROUP BY?
Some databases allow it, treating the entire result set as one group. However, this is generally considered non-standard and not recommended. Always pair HAVING with GROUP BY for clarity and portability.