Union은 서로 다른 테이블로부터 얻은 결과를 합치는 역할을 합니다.

mysql> SELECT title

    -> FROM job

    -> UNION

    -> SELECT task

    -> FROM duty; 

join 역할의 Union:

mysql> SELECT first_name

    -> FROM employee

    -> WHERE (first_name LIKE 'J%')

    -> UNION

    -> SELECT first_name

    -> FROM employee

    -> WHERE (first_name LIKE 'R%');