SQL 20240921

20240921===========================================

-- SQL Lv 2. 카테고리별 상품 개수 구하기

SELECT SUBSTR(PRODUCT_CODE,0,2) AS CATEGORY, COUNT(*) AS PRODUCTS
FROM PRODUCT
GROUP BY SUBSTR(PRODUCT_CODE,0,2)
ORDER BY CATEGORY;

-- SQL Lv 1. 조건에 맞는 회원수 구하기

SELECT COUNT(*) AS USERS
FROM USER_INFO
WHERE AGE BETWEEN 20 AND 29
AND JOINED BETWEEN TO_DATE('2021-01-01','YYYY-MM-DD') AND TO_DATE('2021-12-31','YYYY-MM-DD');

-- SQL Lv 2. 진료과별 총 예약 횟수 출력하기

SELECT MCDP_CD AS "진료과코드", COUNT(*) AS "5월예약건수"
FROM APPOINTMENT
WHERE TO_CHAR(APNT_YMD,'yymm') = '2205'
GROUP BY MCDP_CD
ORDER BY COUNT(*),"진료과코드";