join with same table in mysql?

Question

Im having the following table , each employee have a manager, if a guy is his own manager den the managerid field is null, i want emid name and manager id as result

Answer 1

SELECT emid, name,
       CASE WHEN s.managerid IS NULL THEN s.name ELSE m.name END managername
  FROM employees s
  LEFT JOIN employees m ON s.managerid = m.managerid

OR

SELECT emid, name, m.name managername
  FROM employees s
  LEFT JOIN employees m ON COALESCE(s.managerid, s.emid) = m.emid