Low-Salary Employees with Departed Managers

Easy

An HR analytics warehouse stores active employee rows and keeps each worker's manager ID as a reference. When supervisors leave, their rows are removed from the active table, but direct reports may still carry the old manager_id value. Table: employees employee_id: unique employee identifier name: employee full name manager_id: direct manager ID (NULL for top-level staff) salary: annual salary in dollars Task: Return employee IDs for workers who satisfy both conditions: salary is strictly less than 30000 manager_id is not NULL and points to no current employee row Output requirements: Return exactly one column: employee_id Sort by employee_id in ascending order. Supported submission environments: SQL (SQLite 3.27.2) Pandas (Python)

Example 1

Input

employees:
| employee_id | name      | manager_id | salary |
|-------------|-----------|------------|--------|
| 3           | Mila      | 9          | 60301  |
| 12          | Antonella | null       | 31000  |
| 13          | Emery     | null       | 67084  |
| 1           | Kalel     | 11         | 21241  |
| 9           | Mikaela   | null       | 50937  |
| 11          | Joziah    | 6          | 28485  |

Output

[
  {"employee_id":11}
]

Explanation

Employees 1 and 11 are below 30000. Employee 1 reports to 11, which exists, so it does not qualify. Employee 11 reports to manager 6, which is missing, so it qualifies.

Example 2

Input

employees:
| employee_id | name   | manager_id | salary |
|-------------|--------|------------|--------|
| 101         | Iris   | null       | 21000  |
| 102         | Noor   | 101        | 29999  |
| 103         | Omar   | 999        | 30000  |
| 104         | Pia    | 999        | 29999  |

Output

[
  {"employee_id":104}
]

Explanation

Employee 104 is below 30000 and references missing manager 999. Employee 103 fails because salary is exactly 30000, not strictly lower.

Example 3

Input

employees:
| employee_id | name   | manager_id | salary |
|-------------|--------|------------|--------|
| 10          | Alex   | null       | 25000  |
| 20          | Bea    | 10         | 22000  |
| 30          | Chen   | 20         | 31000  |

Output

[]

Explanation

No row satisfies both conditions at the same time.

Constraints

0 <= number of rows in employees <= 250000
1 <= employee_id <= 1000000000
1 <= length(name) <= 255
manager_id is NULL or in [1, 1000000000]
0 <= salary <= 10000000
employees.employee_id is unique
Salary condition is strict: salary < 30000
manager_id = NULL must not qualify
A manager is departed if no row exists with employee_id = manager_id
Return exactly one column: employee_id
Sort by employee_id ascending
For SQL submissions, use SQLite 3.27.2 semantics
For Pandas submissions, return a DataFrame with column employee_id

employees: | employee_id | name | manager_id | salary | |-------------|-----------|------------|--------| | 3 | Mila | 9 | 60301 | | 12 | Antonella | null | 31000 | | 13 | Emery | null | 67084 | | 1 | Kalel | 11 | 21241 | | 9 | Mikaela | null | 50937 | | 11 | Joziah | 6 | 28485 |

employees: | employee_id | name | manager_id | salary | |-------------|--------|------------|--------| | 101 | Iris | null | 21000 | | 102 | Noor | 101 | 29999 | | 103 | Omar | 999 | 30000 | | 104 | Pia | 999 | 29999 |

employees: | employee_id | name | manager_id | salary | |-------------|--------|------------|--------| | 10 | Alex | null | 25000 | | 20 | Bea | 10 | 22000 | | 30 | Chen | 20 | 31000 |