Explain pandas and SQL basics

Q: Explain pandas and SQL basics

This question evaluates familiarity with pandas data structures (Series vs DataFrame), SQL filtering semantics (WHERE vs HAVING), and practical SQL aggregation for detecting duplicate records, assessing competencies in data manipulation, aggregation, and basic data quality checks.

Q: How do I approach Data Manipulation (SQL/Python) interview questions?

Data Manipulation (SQL/Python) questions require understanding of core concepts and practice. PracHub provides solutions with explanations to help you master data manipulation (sql/python) interviews.

Question

You are interviewing for a Data Engineer co-op/intern role. Answer the following short technical questions.

Python / pandas:

What is the difference between a pandas Series and a pandas DataFrame ? Give one practical example of when you would use each.

SQL concepts: 2. What is the difference between WHERE and HAVING in SQL, and when should each be used?

SQL query task: 3. You have a table:

customer_events

event_id BIGINT
customer_email STRING
source_system STRING
created_at TIMESTAMP

Assume created_at is stored in UTC. Write a SQL query to find duplicate customer_email values in the table. A duplicate means the same customer_email appears more than once in the full table. Return these output columns:

customer_email
duplicate_count

Only include emails that appear more than once.

Explain pandas and SQL basics

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