SQL: Manager of Manager | Dataford Interview Questions

Business Context

Walmart Global Tech maintains an employee hierarchy for organizational reporting. The reporting team needs to display each employee's direct manager and second-level manager, including employees whose hierarchy is incomplete.

Task

Write a PostgreSQL query that returns every employee, their direct manager, and their manager's manager.

Requirements

Use self-joins on the employees table to resolve both management levels.
Preserve employees with no manager or with an unmatched manager record, showing NULL for unavailable names.
Return one row per employee, ordered by employee_id ascending.

Schema

employees

Column	Type	Description
employee_idPK	INT	Unique employee identifier
manager_id	INT	Self-referencing employee ID for the direct manager
employee_name	VARCHAR(100)	Employee's full name

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