How a Single Recursive SQL Query Can Traverse an Entire Org Chart

Hierarchical data structures like employee-manager relationships can be queried efficiently in SQL using a recursive Common Table Expression (CTE). A recursive CTE works by first identifying the top-level rows — in this case, employees with no manager — then repeatedly joining the table back to itself to find each subsequent level of reports. PostgreSQL continues this process until no new rows are returned, effectively walking the entire tree in one query. Additional fields like level and path can be used to control indentation and maintain correct ordering in the output. This approach offers a clean, scalable alternative to writing separate queries for each level of a hierarchy.