Walk a hierarchy recursively in SQL
SQL interview exercise on Subqueries & CTEs, difficulty 3 of 3. Solve it in the editor beside a worked example, or cold in Interview mode with the example hidden; the tests run the moment you do.
Return every employee with their level in the reporting chain: the CEO is 0, their direct reports 1, and so on, however deep it goes. Columns: name, level. Sorted by level, then name.
Each exercise pairs a worked example with a twin problem to solve in a real editor; the tests run the moment you do. Interview mode hides the example: solve it from memory, without the hint or the solution, and it counts as solved cold. Progress is saved in your browser, and in your account if you sign in.