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How do you find the second-highest salary in SQL?
Last Updated: December 2, 2025Finding the second-highest salary in SQL can be done in a few different ways, depending on the database and the...
Explain the CROSS JOIN in SQL.
Last Updated: December 2, 2025A CROSS JOIN in SQL is used to combine every row from one table with every row from another table...
What is the use of RANK() and DENSE_RANK() functions?
Last Updated: December 2, 2025The RANK() and DENSE_RANK() functions in SQL are both window functions used to assign rankings to rows based on a...
What are window functions in SQL?
Last Updated: December 2, 2025Window functions in SQL are powerful analytical functions that perform calculations across a set of rows related to the current...
How do you use COALESCE in SQL?
Last Updated: December 2, 2025The COALESCE function in SQL is used to handle NULL values. It returns the first non-null value from a list...
What is the EXISTS clause? How is it different from IN?
Last Updated: December 2, 2025The EXISTS clause in SQL is used to check whether a subquery returns any records. It returns TRUE if the...
How can you optimize a SQL query?
Last Updated: December 2, 2025key techniques is using proper indexing. For example, if a table has millions of rows and we frequently filter data...
Explain the use of CASE in SQL.
Last Updated: December 2, 2025The CASE statement in SQL is used to add conditional logic inside a query — it’s like an IF-THEN-ELSE structure....
What is the difference between UNION and UNION ALL?
Last Updated: December 2, 2025The main difference between UNION and UNION ALL is how they handle duplicate records. UNION combines the results of two...
What are subqueries in SQL? Explain with an example.
Last Updated: December 2, 2025Subqueries in SQL are basically queries written inside another query. They’re used when we need to use the result of...