fatalite

무결성 제약 조건 및 키 제약 조건 테이블 만들 때 조건 걸기(CREATE TABLE) CREATE TABLE users(user_id int primary key, password int check(password >= 0)); create table users(user_id char(64), constraint pk primary key user_id); CREATE TABLE 테이블_명 ( 컬럼명_첫번째 자료형 제약 조건 , ...); 제약 조건 이름 따로 없는듯? CREATE TABLE 테이블_명 ( 컬럼명_첫번째 자료형, CONSTRAINT 제약_조건이름 제약_조건키워드(PARAMETER) ); 추가적으로 할 때(ALTER TABLE) ALTER TABLE users add phone_numbe..

#1 SELECT LAST_NAME, HIRE_DATE FROM EMPLOYEES WHERE DEPARTMENT_ID = (SELECT DEPARTMENT_ID FROM EMPLOYEES WHERE LAST_NAME = 'Zlotkey') AND LAST_NAME 'Zlotkey'; #2 SELECT EMPLOYEE_ID, LAST_NAME FROM EMPLOYEES WHERE SALARY > (SELECT AVG(SALARY) FROM EMPLOYEES) ORDER BY SALARY; #3 SELECT EMPLOYEE_ID, LAST_NAME FROM EMPLOYEES WHERE DEPARTMENT_ID IN (SELECT DEPARTMENT_ID FROM EMPLOYEES WHERE LAST_NAME..

select * from employees; #1번 문제 select max(salary) as "Maximum", min(salary) as "Minimum", sum(salary) as "Sum", round(Avg(salary)) as "avg" from employees; #2번 문제 select JOB_ID, max(salary) as "Maximum", min(salary) as "Minimum", sum(salary) as "Sum", round(Avg(salary)) as "avg" from employees group by JOB_ID order by JOB_ID; #3번 문제 select JOB_ID, count(JOB_ID) as "count" from employees group b..