SQL Interview - Intermediate Level
For developers with 2-4 years of SQL experience. Master complex JOINs, subqueries, window functions, CTEs, indexes, and query optimization.
25-30 minutes
2-4 years of SQL experience
Who is this for?
Mid-level backend developers
Data analysts with SQL experience
Database developers
Those preparing for mid-senior data roles
What you'll practice
Using all JOIN types effectively
Writing complex subqueries
Working with window functions
Creating CTEs (WITH clause)
Understanding indexes
Optimizing query performance
Topics covered
Advanced JOINs
LEFT, RIGHT, FULL OUTER JOIN
Self JOINs
Multiple table JOINs
CROSS JOIN
Window Functions
ROW_NUMBER, RANK, DENSE_RANK
PARTITION BY
LAG, LEAD
Aggregate window functions
CTEs & Subqueries
Common Table Expressions
Correlated subqueries
EXISTS and NOT EXISTS
Subquery patterns
Performance
Indexes basics
Query optimization
EXPLAIN command
Transaction basics
Example questions
Q:
What is the difference between RANK and DENSE_RANK?
Q:
How do you use window functions with PARTITION BY?
Q:
What are CTEs and when should you use them?
Q:
How does a self JOIN work?
Q:
What are indexes and how do they improve performance?
Q:
How do you optimize a slow query?
Preparation tips
Master all JOIN types
Practice window functions extensively
Learn CTEs and when to use them
Understand index usage
Study query execution plans
Practice complex analytical queries
Continue your journey
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