Real questions from top companies in SQL
When would you choose a Snowflake schema over a Star schema?
Detail examples of inner, outer, left, and right joins.
Difference Between Internal and External Tables in BigQuery
Difference between ROW_NUMBER(), RANK(), and DENSE_RANK() with examples.
Difference between where and having clause with examples.
Explain Common Table Expressions (CTEs) and their benefits.
Explain SQL Window Functions with examples.
Explain the difference between UNION and UNION ALL.
Explain the use of the MERGE statement in SQL.
How do you handle NULL values in SQL? Mention functions like COALESCE and ISNULL.
How do you optimize a long-running SQL query?
How would you handle duplicate records in an SQL table?
Implement a query to find the top 5 customers by total sales amount.
SQL query to find the second highest salary from each department.
What are primary keys and foreign keys? Why are they important?
What is a self-join, and when would you use it?
What is normalization and denormalization? When would you use each?
What is the difference between a clustered and non-clustered index?
What is the difference between a view and a materialized view?
What is the difference between DELETE and TRUNCATE?