PostgreSQL: Appendix of field to sample request from several tables

[amarantha]

Database chart (posgresql):

Student(id, name, last_name, e_mail)
Teacher(id, name, last_name, e_mail, subject)

It is necessary:

Delete alllast_name’ and ‘name’ all ‘Teacher’ and ‘Studentwith field ‘type‘student or teacher. Disorder in alphabetical order by ‘last_name’. It should look like this:

last_name   | type
            | 
Kankava     | teacher
Smith       | student
Sidorov     | teacher
Petrov      | teacher

I don't know how. SELECT Add the column TYPE and tie her to the table?

[elysha]

SELECT * FROM
      (SELECT name, last_name, 'student' AS type FROM Student
        UNION
      SELECT name, last_name, 'teacher' AS type FROM Teacher)
   AS forexempl ORDER BY last_name;