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Google·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
May 2026

Summary

Google data analyst interview with a SQL question that felt more like a CS puzzle than anything I expected for the role.

Questions Asked (1)

Q1

Write a SQL query to generate the Fibonacci series.

Algorithms & Data StructuresData Modeling
Author's notes

I stared at this for a moment because SQL is not where my brain goes for sequence generation.

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AI HintsAI Generated

Suggested Approach

Clarify the SQL dialect and constraints (e.g., max N, recursion support) before writing the query. Use a recursive CTE to generate Fibonacci numbers iteratively, handling the base cases (0 and 1) and then computing subsequent terms. If recursion is not supported, consider a numbers table or a stored procedure with a loop.

Pro tip: Mention that recursive CTEs may hit recursion depth limits, so for large N, an iterative approach in application code or a numbers table is more efficient. Also, discuss the trade-offs between generating the series in SQL versus in application code.

1. Clarify requirements

Ask about the SQL dialect (e.g., PostgreSQL, MySQL, SQL Server), the expected output format (single column of numbers, or with index), and the maximum number of terms needed.

2. Choose generation method

Decide between a recursive CTE, a numbers table with a self-join, or a stored procedure with a loop. Recursive CTE is most common for this problem.

3. Write the query

For recursive CTE: define the anchor member with the first two Fibonacci numbers (0 and 1), then the recursive member that adds the last two numbers until the desired count is reached.

4. Test and optimize

Test with small N to verify correctness, then consider performance for large N. If recursion depth is an issue, suggest alternatives like iterative generation in application code.

Key Points to Mention

  • Recursive CTE syntax and how it works (anchor + recursive member)
  • Handling base cases (0 and 1) correctly
  • Limiting the number of terms using a counter or WHERE clause
  • Dialect-specific features (e.g., WITH RECURSIVE in PostgreSQL, MySQL 8+, SQL Server)
  • Performance considerations and recursion depth limits
  • Alternative approaches (numbers table, stored procedure, application code)

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.