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
Calculate Net Pay Change for Q1 2023 Decreases
Calculate Day-7 Retention Rate from User Post Data
Merge and Clean Customer Order Data for Analysis
Explain Window Functions and Joins in SQL and Python
Calculate and Find Average Contacts and Sync Percentage
Clean and Summarize User Purchase Data Efficiently
Identify Users with Specific Page Navigation Patterns
Merge and Concatenate Inconsistent Order Files with Pandas
Identify Shops with Low Weekly Visibility Rates
Ensure Correct Numeric Ordering in Visit ID Comparison
Identify Key Metrics for Monitoring Shipment Defects
Calculate User Revenue and Session Duration in Python
Visualize and Clean SKU Sales Data for Outliers
Analyze Loan Payments Using Pandas for Key Insights
Select 10% Users Randomly from User Table
Analyze Posting Behavior by Cohort and Date
Analyze Pirate Theme Usage Growth Over Time
Calculate Longest Transaction Streak for Each User
Analyze Bookstore Data to Identify Top Payment Methods
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.