💡 Mastering Hierarchical Data with Recursive CTEs in SQL

One of the most powerful features in SQL is the recursive Common Table Expression (CTE)—perfect for working with hierarchical data like org charts or bill of materials.

Here’s how you can use a recursive CTE to traverse an employee-manager hierarchy and find all reports for a given manager:

WITH RECURSIVE OrgChart AS (
    -- Anchor member: start with the manager
    SELECT employee_id, manager_id, employee_name, 1 AS level
    FROM employees
    WHERE manager_id IS NULL  -- Top-level manager (e.g., CEO)

    UNION ALL

    -- Recursive member: find direct reports
    SELECT e.employee_id, e.manager_id, e.employee_name, oc.level + 1
    FROM employees e
    INNER JOIN OrgChart oc ON e.manager_id = oc.employee_id
)
SELECT * FROM OrgChart
ORDER BY level, manager_id;
        

What this does:

• Starts with the top-level manager (e.g., CEO)
• Recursively finds all direct and indirect reports
• Assigns a “level” to show the hierarchy depth

Recursive CTEs are a game-changer for anyone working with complex data relationships!

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