Real questions from top companies in SQL · easy
Explain the differences between a Data Lake and a Data Warehouse.
Explain the concept of ACID properties in the context of databases.
Explain Common Table Expressions (CTEs) and their benefits.
Explain the difference between UNION and UNION ALL.
What is the difference between a clustered and non-clustered index?
What is the difference between DELETE and TRUNCATE?
What is a CTE (Common Table Expression)? What are its uses?
Aggregate surface areas and calculate cumulative surface area using the LAG function.
Are you comfortable with the variable pay structure, and what are your expectations for the base salary?
CSV Without Column Names/Schema - how to read
Can CASE statements be used in an UPDATE query?
Can you chain multiple triggers for a single pipeline?
Compare Redshift, BigQuery, and Snowflake in terms of cost, performance, and scalability.
Converting SCD0 to SCD3
Describe a cross-team data project where you had to align architectural boundaries, ownership, and SLAs. How did you handle conflicting priorities, technical debt, and the scalability of communication as the number of stakeholders grew?
Walk through a production incident where data freshness or correctness was at risk. How did you balance immediate mitigation vs. root-cause remediation? What architectural changes would prevent recurrence, and what are the cost vs. reliability trade-offs?
Given a dataset, perform transformations: Filter rows where sales > 1000, Add a new column calculating a 10% discount on sales, Group data by region and calculate total revenue.
How do you count occurrences in a column in SQL?
How do you interact with Google BigQuery using Python?
How do you keep a specific column on top in SQL?
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