Real questions from top companies in SQL · medium
Find average salary for each manager – Assume a table with manager_id and employee_salary
Find each student's previous year's scores using the LAG function.
Find employees who earn the third-highest salary.
Find the 2nd highest salary for each department using the DENSE_RANK() function.
Find the error in the provided SQL query.
Find the second-highest salary in the employees table using three different methods.
Find the third-highest salary for each department.
Finding nth Highest Salary within each department
Given a complex nested query, how would you refactor it for better readability and efficiency?
Given a table of sales data, use window functions to calculate a running total.
Given a table with 10 records and another with 4 records, how many records result from a cross join?
Given a table with sales data, write a query to find consecutive days with decreasing revenue.
Given an unoptimized query execution plan, how would you diagnose and improve performance?
Given the data below, explain the results of different types of joins: Inner Join, Left Join, Right Join. Will a schema be created?
Given two dataframes (df1: id, name and df2: id, country, address, city, count), join them, filter for rows where country = 'Singapore', and pivot the output. Sort cities in descending order of population count
Given two tables, calculate the row count for different types of joins (inner, left, right, and full outer)
Handle nulls, duplicates, and inconsistent timestamp formats in data.
Hierarchical Employee-Manager Query - navigate hierarchy with head of company as employee_id = 1
How can you delete partitions from a table in Hive using a command?
How do partitioning strategies differ between source and sink?
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