Employees Without a Manager

Problem

In a company's org chart, top-level executives and founders typically have no manager — their manager_id is NULL because no one is above them in the hierarchy. When HR builds an organizational tree or audits reporting relationships, they start by identifying these root nodes. Using the employees table, return id and name for every employee whose manager_id is NULL, ordered by name.

Schema

employees

column	type
id	INTEGER
name	TEXT
department	TEXT
salary	INTEGER
manager_id	INTEGER (NULL if no manager)

Sample Data

id	name	department	salary	manager_id
1	Alice	Engineering	150000	NULL
2	Bob	Engineering	100000	1
3	Carol	HR	120000	NULL
4	Dave	Marketing	90000	3

Expected Output

id	name
1	Alice
3	Carol