20241002

🖥️ 1.Today I Learned

-알고리즘,SQL 문제 풀기

https://school.programmers.co.kr/learn/courses/30/lessons/59415

SELECT DATETIME FROM ANIMAL_INS ORDER BY DATETIME DESC LIMIT 1;

https://school.programmers.co.kr/learn/courses/30/lessons/164670

SELECT u.USER_ID, 
       u.NICKNAME, 
       CONCAT(u.CITY, u.STREET_ADDRESS1, u.STREET_ADDRESS2) AS 전체주소, 
       CONCAT(SUBSTRING(u.TLNO, 1, 3), '-', SUBSTRING(u.TLNO, 4, 4), '-', SUBSTRING(u.TLNO, 8, 4))AS 전화번호
FROM USED_GOODS_USER u
INNER JOIN (
    SELECT WRITER_ID 
    FROM USED_GOODS_BOARD 
    GROUP BY WRITER_ID 
    HAVING COUNT(WRITER_ID) >= 3
) b ON u.USER_ID = b.WRITER_ID
ORDER BY u.USER_ID DESC;

=> CONCAT(LEFT(u.TLNO, 3), "-", MID(u.TLNO, 4, 4), "-", RIGHT(u.TLNO, 4)) AS 전화번호 이렇게 했는데 오답으로 나와서 substring으로 함 자르고싶으면 substring으로 함