문제
풀이
SELECT USER_ID, NICKNAME,
CONCAT(CITY,' ',STREET_ADDRESS1,' ',STREET_ADDRESS2) AS '전체주소',
CONCAT(left(TLNO,3),'-',mid(TLNO,4,4),'-',right(TLNO,4)) AS '전화번호'
# CONCAT(SUBSTR(TLNO,1,3),'-',SUBSTR(TLNO,4,4),'-',SUBSTR(TLNO,8,4)) AS 전화번호 도 가능
FROM USED_GOODS_BOARD B INNER JOIN USED_GOODS_USER U
ON B.WRITER_ID = U.USER_ID
GROUP BY WRITER_ID
HAVING COUNT(WRITER_ID) >= 3
ORDER BY USER_ID DESC
- CONCAT
- CONCAT('h', 'e', 'l') > 'hel'
- SUBSTRING
- SUBSTRING(문자열, 시작 위치, 반환할 문자 개수)
- SUBSTRING('hello world', 1, 4) > 'hello'
참고