SOLVESQL

지역별 주문의 특징

SELECT REGION AS "Region"
	   , (SELECT COUNT(DISTINCT ORDER_ID) FROM RECORDS A WHERE Z.REGION = A.REGION AND CATEGORY = 'Furniture') AS Furniture
	   , (SELECT COUNT(DISTINCT ORDER_ID) FROM RECORDS A WHERE Z.REGION = A.REGION AND CATEGORY = 'Office Supplies') AS "Office Supplies"
	   , (SELECT COUNT(DISTINCT ORDER_ID) FROM RECORDS A WHERE Z.REGION = A.REGION AND CATEGORY = 'Technology') AS Technology
FROM RECORDS Z 
GROUP BY REGION 
ORDER BY REGION;

한 주문에 같은 카테고리를 여러제품 구매했더라도 1개로 가정
https://solvesql.com/problems/characteristics-of-orders/

레스토랑 웨이터의 팁 분석

SELECT DAY
       , TIME
       , ROUND(AVG(TIP), 2) AS AVG_TIP
       , ROUND(AVG(SIZE), 2) AS AVG_SIZE
FROM TIPS
GROUP BY DAY,TIME
ORDER BY DAY,TIME;

https://solvesql.com/problems/tip-analysis/

버뮤다 삼각지대에 들어가버린 택배

SELECT DATE(ORDER_DELIVERED_CARRIER_DATE) AS delivered_carrier_date
	   , COUNT(ORDER_ID) AS orders 
FROM OLIST_ORDERS_DATASET 
WHERE ORDER_DELIVERED_CUSTOMER_DATE IS NULL
AND ORDER_DELIVERED_CARRIER_DATE LIKE '2017-01%' 
GROUP BY DATE(ORDER_DELIVERED_CARRIER_DATE)
ORDER BY ORDER_DELIVERED_CARRIER_DATE;

https://solvesql.com/problems/shipment-in-bermuda/

가구 판매의 비중이 높았던 날 찾기

SELECT 
order_date AS "order_date", Furniture, ROUND((furniture*1.0/ALL_ORDERS*100), 2) AS furniture_pct
FROM
(
SELECT ORDER_DATE
, COUNT(DISTINCT ORDER_ID) ALL_ORDERS
, (SELECT COUNT(DISTINCT ORDER_ID) FROM RECORDS A WHERE CATEGORY = 'Furniture' AND A.ORDER_DATE = Z.ORDER_DATE) AS furniture
FROM RECORDS Z
GROUP BY ORDER_DATE
HAVING ALL_ORDERS >= 10
)
WHERE ROUND((furniture*1.0/ALL_ORDERS*100), 2) >= 40
ORDER BY ROUND((furniture*1.0/ALL_ORDERS*100), 2) DESC , ORDER_DATE;

정수를 실수로 만들기 위해 1.0 곱하기
https://solvesql.com/problems/day-of-furniture/

쇼핑몰의 일일 매출액

SELECT DATE(A.ORDER_PURCHASE_TIMESTAMP) AS dt
       , ROUND(SUM(PAYMENT_VALUE), 2) AS revenue_daily 
FROM OLIST_ORDERS_DATASET A, OLIST_ORDER_PAYMENTS_DATASET B
WHERE A.ORDER_ID = B.ORDER_ID
AND A.ORDER_PURCHASE_TIMESTAMP > '2018-01-01' 
GROUP BY DATE(A.ORDER_PURCHASE_TIMESTAMP)
ORDER BY ROUND(SUM(PAYMENT_VALUE), 2) ;

https://solvesql.com/problems/olist-daily-revenue/

쇼핑몰의 일일 매출액과 ARPPU

SELECT DATE(A.order_purchase_timestamp) AS dt
	   , COUNT(DISTINCT B.ORDER_ID) AS pu, ROUND(SUM(B.payment_value), 2) AS revenue_daily
       , ROUND((SUM(B.payment_value) / COUNT(DISTINCT B.ORDER_ID)), 2) AS arppu
FROM olist_orders_dataset A, olist_order_payments_dataset B 
WHERE A.order_id = B.order_id
AND A.order_purchase_timestamp > '2018-01-01'
GROUP BY DATE(A.order_purchase_timestamp)
ORDER BY DATE(A.order_purchase_timestamp);

https://solvesql.com/problems/daily-arppu/

두 테이블 결합하기

SELECT A.ATHLETE_ID 
FROM RECORDS A, EVENTS B 
WHERE A.EVENT_ID = B.ID 
AND B.SPORT = 'Golf'
GROUP BY A.ATHLETE_ID;

https://solvesql.com/problems/join/

몇 분이서 오셨어요?

SELECT * FROM TIPS WHERE MOD(SIZE, 2) = 1;

https://solvesql.com/problems/size-of-table/

데이터 그룹으로 묶기

SELECT QUARTET
	   , ROUND(AVG(X), 2) AS x_mean
	   , ROUND(VARIANCE(X), 2) AS x_var
	   , ROUND(AVG(Y), 2) AS y_mean
	   , ROUND(VARIANCE(Y), 2) AS y_var 
FROM POINTS 
GROUP BY QUARTET;

https://solvesql.com/problems/group-by/
표본분산 함수 참고
http://bigdata.dongguk.ac.kr/lectures/DB/_book/MySQL1.html 의 3.5.1

최근 올림픽이 개최된 도시

SELECT YEAR, UPPER(SUBSTR(CITY, 0, 4)) AS CITY 
FROM GAMES 
WHERE YEAR >= 2000
GROUP BY YEAR, SUBSTR(CITY, 0, 4)
ORDER BY YEAR DESC ;

https://solvesql.com/problems/olympic-cities/

우리 플랫폼에 정착한 판매자 1

SELECT SELLER_ID, COUNT(DISTINCT ORDER_ID) AS ORDERS
FROM OLIST_ORDER_ITEMS_DATASET
GROUP BY SELLER_ID
HAVING COUNT(DISTINCT ORDER_ID) >= 100;

https://solvesql.com/problems/settled-sellers-1/

최고의 근무일을 찾아라

SELECT day, SUM(TIP) AS tip_daily  
FROM TIPS 
GROUP BY DAY 
ORDER BY SUM(TIP) DESC 
LIMIT 1

https://solvesql.com/problems/best-working-day/

멘토링 짝꿍 리스트

SELECT A.EMPLOYEE_ID AS MENTEE_ID
	   , A.NAME AS MENTEE_NAME
       , B.EMPLOYEE_ID AS MENTOR_ID
       , B.NAME AS MENTOR_NAME
FROM 
(SELECT * FROM EMPLOYEES WHERE JOIN_DATE BETWEEN '2021-09-31' AND '2021-12-31') A,
(SELECT * FROM EMPLOYEES WHERE JOIN_DATE <= '2019-12-31') B
WHERE A.DEPARTMENT <> B.DEPARTMENT
GROUP BY MENTEE_ID, MENTOR_ID
ORDER BY MENTEE_ID, MENTOR_ID;

https://solvesql.com/problems/mentor-mentee-list/

점검이 필요한 자전거 찾기

SELECT BIKE_ID 
FROM RENTAL_HISTORY 
WHERE RENT_AT LIKE '2021-01%'
GROUP BY BIKE_ID
HAVING SUM(DISTANCE) >= 50000 ;

https://solvesql.com/problems/inspection-needed-bike/

첫 주문과 마지막 주문

SELECT DATE(MIN(ORDER_PURCHASE_TIMESTAMP)) AS FIRST_ORDER_DATE
       , DATE(MAX(ORDER_PURCHASE_TIMESTAMP)) AS LAST_ORDER_DATE 
FROM OLIST_ORDERS_DATASET ;

https://solvesql.com/problems/first-and-last-orders/

배송 예정일 예측 성공과 실패

SELECT DATE(X.ORDER_PURCHASE_TIMESTAMP) AS PURCHASE_DATE
	   , IFNULL(SUM(CASE WHEN ORDER_ESTIMATED_DELIVERY_DATE >= ORDER_DELIVERED_CUSTOMER_DATE THEN 1 END), 0) AS SUCCESS
	   , IFNULL(SUM(CASE WHEN ORDER_ESTIMATED_DELIVERY_DATE < ORDER_DELIVERED_CUSTOMER_DATE THEN 1 END), 0) AS FAIL
FROM OLIST_ORDERS_DATASET X
WHERE X.ORDER_PURCHASE_TIMESTAMP LIKE '2017-01%'
AND X.ORDER_ESTIMATED_DELIVERY_DATE IS NOT NULL
AND X.ORDER_DELIVERED_CUSTOMER_DATE IS NOT NULL
GROUP BY DATE(X.ORDER_PURCHASE_TIMESTAMP)
ORDER BY DATE(X.ORDER_PURCHASE_TIMESTAMP) ;

https://solvesql.com/problems/estimated-delivery-date/

많이 주문한 테이블 찾기

SELECT TOTAL_BILL, TIP, SEX, SMOKER, DAY, TIME, SIZE 
FROM
(
	SELECT *, AVG(TOTAL_BILL) OVER() AS AVG_BILL 
    FROM TIPS
) WHERE TOTAL_BILL > AVG_BILL;

https://solvesql.com/problems/find-tables-with-high-bill/
다른방법이 있을듯 보임..
OVER() : 집계함수 결과값을 전체 ROW에서 조회할때 쓰는 함수

레스토랑의 대목

SELECT * FROM TIPS
WHERE DAY IN (SELECT DAY FROM TIPS GROUP BY DAY HAVING SUM(TOTAL_BILL) >= 1500);

https://solvesql.com/problems/high-season-of-restaurant/

레스토랑의 요일별 VIP

SELECT * FROM TIPS
WHERE TOTAL_BILL IN (SELECT MAX(TOTAL_BILL) FROM TIPS GROUP BY DAY);

https://solvesql.com/problems/restaurant-vip/

레스토랑의 요일별 매출 요약

SELECT ROUND(AVG(SUM_TOTAL), 2) FROM
(SELECT SUM(TOTAL_BILL) AS SUM_TOTAL FROM TIPS GROUP BY DAY
);

https://solvesql.com/problems/sales-summary/
뭘 묻는건지..?