when use self join code example

Example 1: self join example

SELECT
    e.first_name + ' ' + e.last_name employee,
    m.first_name + ' ' + m.last_name manager
FROM
    sales.staffs e
INNER JOIN sales.staffs m ON m.staff_id = e.manager_id
ORDER BY
    manager;

Example 2: self join

SELECT column_name(s)
FROM table1 T1, table1 T2
WHERE condition;