그룹 테이블 함수 조작
데이터셋 DROP TABLE IF EXISTS review; CREATE TABLE review ( user_id varchar(255) , product_id varchar(255) , score numeric ); INSERT INTO review VALUES ('U001', 'A001', 4.0) , ('U001', 'A002', 5.0) , ('U001', 'A003', 5.0) , ('U002', 'A001', 3.0) , ('U002', 'A002', 3.0) , ('U002', 'A003', 4.0) , ('U003', 'A001', 5.0) , ('U003', 'A002', 4.0) , ('U003', 'A003', 4.0) ; SELECT count(*) AS total_count , c..
2022. 3. 7.
