oracle

📌 oracle 비빌번호 변경

hr 비밀번호 까먹어서 다시 설정했다

https://ninetynine-2026.tistory.com/363

[oracle] sql system 계정 비밀번호 분실시

 

SELECT
    * FROM employees;
    
SELECT department_id 
from departments;

-- join + where 사용
SELECT 
dep.manager_id , dep.department_id , dep.department_name
, emp.manager_id
from departments dep 
JOIN employees emp
on dep.manager_id = emp.manager_id
WHERE dep.department_name = 'IT'
;

-- 다중 join
select
    dep.department_name, emp.first_name, emp.last_name
    , loc.city
from departments dep
join employees emp
on dep.department_id = emp.department_id
join locations loc
on dep.location_id = loc.location_id
;

-- outer join : 조인의 조건에 만족되지 않은 행(null)까지 포함시키는 것
select
    emp.first_name, emp.last_name, dep.department_name, emp.manager_id
    , loc.city
from departments dep
left OUTER join employees emp
on dep.department_id = emp.department_id
join locations loc
on dep.location_id = loc.location_id
;