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그룹별 리텐션을 확인하는 두가지 방법이다.-- 1번 쿼리with event_first as ( select user_id, `group`, event_date, min(event_date) over (partition by e.user_id) as first_event from abtest.events e left join abtest.users u using(user_id)), user_retention as ( select `group`, user_id, min(event_date) as next_event from event_first where event_date > first_event and event_date -- 2번 쿼리with user_first_event as ( select user..

테크/SQL 2025. 2. 9. 14:48

먼저 기본 테이블로 USERS, EVENTS가 있다고 가정한다.USERSuser_idgroupsignup_date1A2024-09-012B2024-09-013A2024-09-024B2024-09-025C2024-09-026A2024-09-037B2024-09-038A2024-09-039B2024-09-0310C2024-09-0311C2024-09-0312C2024-09-03 EVENTSevent_iduser_idevent_typeevent_valueevent_date11viewnull2024-09-0521purchase100.002024-09-0534viewnull2024-09-0542viewnull2024-09-0553purchase150.002024-09-0664purchase200.002024-09..

테크/SQL 2025. 2. 9. 14:46

SUBSTR, SUBSTRING문자열 내 위치기반 원하는 만큼 가져옴SELECT SUBSTR("가나다라마바사아자", 2, 3);// 결과: 나다라SELECT SUBSTR("가나다라마바사아자", 5);// 결과: 마바사아자 SUBSTRING_INDEX구분자를 사용하여 문자열을 자르지만, 제거하지는 않음SELECT SUBSTRING_INDEX('강감찬-허준-비-이순신-박찬호-강호동-신사임당-이황-이성계', '-', 3);// 결과: 강감찬-허준-비SELECT SUBSTRING_INDEX('강감찬-허준-비-이순신-박찬호-강호동-신사임당-이황-이성계', '-', -4);// 결과: 강호동-신사임당-이황-이성계      추가 예정입니다.

테크/SQL 2025. 2. 9. 14:26