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DB: hr 사용 예제, group by, 내장함수(sum,avg,max,count)

-- --SELECT * FROM employees; -- --select EMPLOYEE_ID, last_name from employees; -- --SELECT job_id FROM employees; -- ---- DisTinct 중복된 데이터 제거 --SELECT DISTINCT job_id FROM employees; --* NOT 연산자 SELECT department_id, DEPARTMENT_NAME FROM DEPARTMENTS -- WHERE NOT department_id = 10; where department_id 10; select * from EMPLOYEES; --* IS Not null SELECT employee_id, last_name, commission_pct FR..
DB 2021. 2. 8. 00:45
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