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SQL and Database Interview Questions
Data Analyst • 2 Questions
Detailed sql and database interview questions and answers for data analyst positions.
Q
Explain the difference between INNER JOIN and LEFT JOIN.
A
INNER JOIN returns only matching records from both tables. LEFT JOIN returns all records from the left table and matching records from the right table, with NULL values for non-matching right table columns. Use INNER JOIN when you need only matching data, LEFT JOIN when you need all records from the primary table.
Q
How do you handle missing data in analysis?
A
Strategies include: 1) Deletion: remove rows/columns with missing data 2) Imputation: fill with mean, median, mode, or predictive values 3) Interpolation: estimate based on surrounding data points 4) Flag creation: create indicator variables for missingness. Choice depends on data type, missing pattern, and analysis requirements.
Mastering SQL and Database for Data Analyst Interviews
SQL and Database questions are fundamental to data analyst interviews. These questions test your understanding of core concepts and your ability to apply them in real-world scenarios.
How to Prepare
- Understand the fundamentals: Make sure you have a solid grasp of basic concepts
- Practice explaining: Be able to explain complex topics in simple terms
- Use examples: Support your answers with concrete examples from your experience
- Stay current: Keep up with industry trends and best practices
Common Mistakes to Avoid
- Giving overly technical answers without context
- Not providing specific examples or use cases
- Focusing only on theory without practical application
- Not asking clarifying questions when needed