DB_010_mySQL_subQuery

SUB_Query

• query 안 에 query를 넣어 조회한다.
• having을 써도 같은결과를 도출할 수 있다.

sub_query_code

SELECT *
FROM (
    SELECT D.name AS `부서명`,
    GROUP_CONCAT(E.`name`) AS `사원리스트`,
    TRUNCATE(AVG(E.salary), 0) AS `평균연봉`,
    MAX(E.salary) AS `최고연봉`,
    MIN(E.salary) AS `최소연봉`,
    COUNT(*) AS `사원수`
    FROM emp AS E
    INNER JOIN dept AS D
    ON E.deptId = D.id
    WHERE 1
    GROUP BY E.deptId
) AS D
WHERE D.`평균연봉` >= 5000;

having_query_code

SELECT D.name AS 부서,
GROUP_CONCAT(E.name) AS 사원리스트,
TRUNCATE(AVG(E.salary), 0) AS 평균연봉,
MAX(E.salary) AS 최고연봉,
MIN(E.salary) AS 최소연봉,
COUNT(*) AS 사원수
FROM emp AS E
INNER JOIN dept AS D
ON E.deptId = D.id
GROUP BY E.deptId
HAVING `평균연봉` >= 5000;