#1 SQL Select 잘 이용하기

출처: https://stricky.tistory.com/204

CREATE TABLE select_test
(
    name    varchar(50),
    dept_cd varchar(1),
    phone   varchar(15),
    address varchar(100)
);

DESC select_test;

DESC: 테이블 칼럼 목록 조회

INSERT INTO select_test(name, dept_cd, phone, address) VALUES('eileen', 'A', 01011112222, 'gangnam-gu');
SELECT name, phone FROM select_test;
SELECT * FROM select_test WHERE dept_cd == 'A';

projection & selection 예시

SELECT name, '님 반갑습니다 :)' as expression FROM select_test;
SELECT DISTINCT dept_cd FROM select_test;

alias 별명 붙이기 & 중복 제거

SELECT CONCAT(name, '의 부서코드는', dept_cd, '입니다') FROM select_test;
SELECT name || '의 부서코드는' || dept_cd || '입니다' FROM select_test;
SELECT name || '의 부서코드는 ' || dept_cd || '입니다' FROM select_test WHERE name == '손흥민';

한문장으로 합치기 & where 절 적용해서 selection 해보기