[링크] MySql 에서 그룹별 랭킹(그룹 내 랭킹) 구하기
https://blackbull.tistory.com/43
https://blackbull.tistory.com/43
해당 탐색기 빈 곳에 ‘우클릭 > 분류 방법 > 없음’ 클릭
https://stackoverflow.com/questions/276927/can-i-concatenate-multiple-mysql-rows-into-one-field
https://medium.com/@nomanr/constraintlayout-chains-4f3b58ea15bb