juniorSQL
What is a primary key in SQL?
Updated Feb 20, 2026
Short answer
Concise explanation of core concept in SQL.
Deep explanation
Deep explanation covering architecture, performance implications, tradeoffs, scalability, and production considerations in SQL.
Real-world example
In production, teams apply SQL principles to build scalable, fault-tolerant systems handling millions of users.
Common mistakes
- Common mistakes include shallow understanding, ignoring edge cases, and not considering performance bottlenecks.
Follow-up questions
- How would you scale this?
- What are trade-offs?
- How would you debug production issues?
- How does this compare to alternatives?