Third Highest Value with PySpark | Dataford Interview Questions

Your question is Third Highest Value with PySpark. Start with the requirements and the three tables on the right.

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Problem

CGI Group needs a compensation report for active employees in Canadian offices. Write a PostgreSQL query that returns one salary value based on the distinct eligible salaries.

Requirements

Join employees to their departments and offices.
Include only employees with employment_status = 'Active', a non-NULL salary, and an office in Canada.
Rank distinct salaries from highest to lowest, so duplicate employee salaries count once.
Return the third-highest distinct salary when at least three exist. If exactly two exist, return the second-highest. If exactly one exists, return that salary. Return NULL when no eligible salary exists.
Return one row with the exact output column selected_salary.

Schema

employees

Column	Type	Description
employee_idPK	INT	Employee identifier
employee_name	VARCHAR(100)	Employee name
department_id	INT	References departments.department_id
salary	NUMERIC(12,2)	Annual employee salary
employment_status	VARCHAR(20)	Current employment status

departments

Column	Type	Description
department_idPK	INT	Department identifier
department_name	VARCHAR(100)	Department name
office_id	INT	References offices.office_id

offices

Column	Type	Description
office_idPK	INT	Office identifier
office_name	VARCHAR(100)	Office name
country	VARCHAR(50)	Office country
city	VARCHAR(80)	Office city