Pairs of Employees in the Same Department

Return every unordered pair of employees working in the same department, once, with the smaller id first. Order by the first id, then the second.

Table schema

Employees(id INT PRIMARY KEY, name VARCHAR(50), department_id INT)

Sample data

id | name | department_id
1 | A | 1
2 | B | 1
3 | C | 1
4 | D | 2