관재탑

https://www.hackerrank.com/challenges/earnings-of-employees/problem?isFullScreen=true Top Earners | HackerRank Find the maximum amount of money earned by any employee, as well as the number of top earners (people who have earned this amount). www.hackerrank.com 문제 We define an employee's total earnings to be their monthly worked, and the maximum total earnings to be the maximum total earnings fo..

SQL/MySQL 문제풀이 2022. 7. 18. 18:53

1.집계함수 1-1. COUNT() : 컬럼의 개수를 세준다. 1-2. AVG() : 컬럼이 평균을 구해준다. 1-3. SUM(), MAX(), MIN()의 함수도 있다. 2. GROUP BY, HAVING WHERE은 GROUP BY위에 HAVING은 밑에 적어준다. WHERE은 GROUP BY에 들어가기 전에 필터를 걸어준다. HAVING은 GROUP BY로 나온 결과에 필터를 걸어준다. SELECT SupplierID, CategoryID, ROUND(AVG(Price)) FROM Products WHERE Price >= 20 GROUP BY SupplierID, CategoryID HAVING ROUND(AVG(Price)) >= 40 ORDER BY ROUND(AVG(Price)) DESC G..

SQL/MySQL 이론 2022. 7. 18. 17:06

https://www.hackerrank.com/challenges/weather-observation-station-15/problem?isFullScreen=true Weather Observation Station 15 | HackerRank Query the Western Longitude for the largest Northern Latitude under 137.2345, rounded to 4 decimal places. www.hackerrank.com 문제 Query the Western Longitude (LONG_W) for the largest Northern Latitude (LAT_N) in STATION that is less than . Round your answer to..

SQL/MySQL 문제풀이 2022. 7. 18. 16:36

https://www.hackerrank.com/challenges/more-than-75-marks/problem?isFullScreen=true Higher Than 75 Marks | HackerRank Query the names of students scoring higher than 75 Marks. Sort the output by the LAST three characters of each name. www.hackerrank.com 문제 Query the Name of any student in STUDENTS who scored higher than Marks. Order your output by the last three characters of each name. If two or..

SQL/MySQL 문제풀이 2022. 7. 18. 16:34

https://www.hackerrank.com/challenges/weather-observation-station-12/problem?isFullScreen=true Weather Observation Station 12 | HackerRank Query an alphabetically ordered list of CITY names not starting and ending with vowels. www.hackerrank.com 문제 Query the list of CITY names from STATION that do not start with vowels and do not end with vowels. Your result cannot contain duplicates. 정답쿼리 SELEC..

SQL/MySQL 문제풀이 2022. 7. 18. 15:37

https://www.hackerrank.com/challenges/weather-observation-station-6/problem?isFullScreen=true Weather Observation Station 6 | HackerRank Query a list of CITY names beginning with vowels (a, e, i, o, u). www.hackerrank.com 문제 Query the list of CITY names starting with vowels (i.e., a, e, i, o, or u) from STATION. Your result cannot contain duplicates. 정답 쿼리 SELECT DISTINCT CITY FROM STATION WHERE..

SQL/MySQL 문제풀이 2022. 7. 18. 15:24

1. 비교연산자 : 특정 컬럼이 특정 값을 가지는 데이터만 불러오기 위해서 사용 =, , >=, , = 3 AND CustomerID 2014 2. RIGHT(컬럼명 또는 문자열, 문자열의 길이) ex) SELECT RIGHT('20140323', 4) => 0323 3. SUBSTR(컬럼명 또는 문자열, 시작위치, 길이) ex) SUBSTR('20140323', 1, 4) => 2014 ex) SUBSTR('20140323', 5) => 0323 9. 소수점처리 1. CEIL() : 올림 ex) SELECT CEIL(5.5) => 6 2. FLOOR() : 내림 ex) SELECT FLOOR(5.5) => 5 3. ROUND() : 반올림 ex) ROUND(5.556901, 4) => 5.5569

SQL/MySQL 이론 2022. 7. 18. 15:02