[SQL] Concat, Alias, Distinct, Limit

📌 CONCAT

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• 여러 문자열을 하나로 합치거나 연결

select concat('string1', 'string2',...);

✏️예시

select concat('이름:', name) from celeb;

📌 ALIAS

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• 칼럼이나 테이블 이름에 별칭 생성

select column as '별칭'
from tablename;

select column1, column2,...
from tablename as '별칭';

✏️예시

select name as '이름' from celeb;

🚨as는 생략가능하다🚨

select s.season, s.episode, c.name, c.job_title
from celeb as c, snl_show as s
where c.name = s.host;

📌 DISTINCT

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• 검색한 결과의 중복 제거

select distinct column1, column2,...
from tablename;

📌 LIMIT

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• 검색결과를 정렬된 순으로 주어진 숫자만큼만 조회

select column1, column2,...
from tablename
where condition
limit number;