Real questions from top companies in SQL · medium
How do you handle NULL values in SQL? Mention functions like COALESCE and ISNULL.
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 view and a materialized view?
Write an SQL query to find duplicate emails in a users table.
Triggers in ADF, especially tumbling window triggers.
What is a window function? Explain with an example.
What is the difference between OLTP and OLAP?
Write a SQL query to find top 3 earners in each department.
Write a query to find the top three highest-paid employees in each department using window functions.
Write complex SQL queries involving multiple joins, subqueries, and data aggregation logic.
Add Row Numbers using window function in PySpark
Add a column to the Employees table that shows the name of the employee with the next higher employee_id.
Add a new column with manager names for each employee using a self-join.
Add a new column with the average salary by department.
Advanced SQL with CTEs and Conditional Joins
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