Explain the difference between joins and subqueries?
A technical SQL question assessing database query optimization and structural understanding.
Why Interviewers Ask This
Efficient data retrieval is crucial. Interviewers want to know if you understand performance implications and readability trade-offs between different query structures.
How to Answer This Question
Define joins as combining tables based on related columns. Define subqueries as nested queries returning single values or lists. Discuss performance differences and readability.
Key Points to Cover
- Definition of joins
- Definition of subqueries
- Performance comparison
Sample Answer
Joins combine rows from multiple tables based on a related column, often more efficient for large datasets. Subqueries are nested queries useful for filtering or calculations. Joins are generally preferred for readabilit…
Common Mistakes to Avoid
- Confusing inner and outer joins
- Ignoring performance impact
- Poor syntax explanation
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