Group By vs Having in Reporting | Dataford Interview Questions

Your question is Group By vs Having in Reporting. Take a moment with it on the right.

Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).

Problem

Context

In reporting queries, you often need to summarize rows first and then decide which summarized groups should appear in the result. This is a common source of confusion in PostgreSQL interviews.

Core question

Explain the difference between GROUP BY and HAVING using a practical scenario. You should describe what each clause does, when each is evaluated, and why HAVING is not the same as WHERE. Use a simple reporting example such as finding Coforge order categories with more than a certain number of orders or total revenue above a threshold.

Scope guidance

Keep your answer focused on single-table aggregation. A strong answer should define both clauses clearly, show a short PostgreSQL example, and explain why WHERE filters rows before grouping while HAVING filters groups after aggregation.

Your question is Group By vs Having in Reporting. Take a moment with it on the right.

Talk me through your thinking if you like. When you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes).

Context

In reporting queries, you often need to summarize rows first and then decide which summarized groups should appear in the result. This is a common source of confusion in PostgreSQL interviews.