Return each department_id together with how many employees it has.
Return two columns: the department id, then the count. Skip the employee with no department.
Example 1
Return exactly two columns: department_id, then the count.Exclude rows where department_id is NULL.Row order does not matter.Loading tables…
CREATE TABLE departments (
id INTEGER PRIMARY KEY,
name TEXT NOT NULL
);
CREATE TABLE employees (
id INTEGER PRIMARY KEY,
name TEXT NOT NULL,
department_id INTEGER,
salary INTEGER NOT NULL,
hired_on TEXT NOT NULL
);
INSERT INTO departments (id, name) VALUES
(1, 'Engineering'),
(2, 'Sales'),
(3, 'Support');
INSERT INTO employees (id, name, department_id, salary, hired_on) VALUES
(1, 'Ana Reyes', 1, 72000, '2021-03-15'),
(2, 'Ben Cruz', 1, 68000, '2020-07-01'),
(3, 'Carla Diaz', 2, 54000, '2022-01-20'),
(4, 'Dino Lim', 2, 51000, '2019-11-05'),
(5, 'Elena Santos', 3, 47000, '2023-06-12'),
(6, 'Frank Uy', 1, 95000, '2018-02-28'),
(7, 'Grace Tan', 3, 49000, '2022-09-30'),
(8, 'Hector Ramos', NULL, 60000, '2024-01-08');