Show employees and their grandmanagers
Return every employee ID, employee name, manager name, and grandmanager name. Preserve employees without a manager or grandmanager and show missing names as NULL. Return only the requested columns and follow the specified ordering. This question probes two left self joins traverse exactly two reporting edges while preserving incomplete chains.
Input
Setup script defining employees(id INT, name VARCHAR(30), department_id INT, manager_id INT, salary INT).
Output
id, employee_name, manager_name, grandmanager_name; ascending employee ID.
Constraints
0–10000 rows per table. IDs are unique and non-NULL unless stated otherwise; foreign keys may be NULL. Numeric amounts are integers from 0 to 1000000. Dates are valid YYYY-MM-DD text. Text uses case-sensitive comparison; test data has consistent case. Duplicate business values and NULLs are allowed unless excluded by the task.
Example
Tables and sample rows
CREATE TABLE employees(id INT, name VARCHAR(30), department_id INT, manager_id INT, salary INT); INSERT INTO employees VALUES (1,'Ana',10,NULL,100),(2,'Ben',10,1,200),(3,'Cara',20,1,200),(4,'Dan',20,3,300),(5,'Eve',NULL,NULL,NULL);
Expected result
id | employee_name | manager_name | grandmanager_name 1 | Ana | NULL | NULL 2 | Ben | Ana | NULL 3 | Cara | Ana | NULL 4 | Dan | Cara | Ana 5 | Eve | NULL | NULL
Another dataset (1)
CREATE TABLE employees(id INT, name VARCHAR(30), department_id INT, manager_id INT, salary INT); INSERT INTO employees VALUES (1,'Solo',10,NULL,100),(2,'Twin',10,1,100),(3,'Null',NULL,NULL,NULL);
Expected result
id | employee_name | manager_name | grandmanager_name 1 | Solo | NULL | NULL 2 | Twin | Solo | NULL 3 | Null | NULL | NULL
Covers missing matches, ties, or NULL values without relying on insertion order.
Hints (2)
- Use a separate alias for each hierarchy level.
- Both joins must be LEFT JOINs.
Target complexity: time O(n^2) · space O(n)