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https://leetcode.com/problems/monthly-transactions-i/submissions/1193358504/?envType=study-plan-v2&envId=top-sql-50 Monthly Transactions I - LeetCode Can you solve this real interview question? Monthly Transactions I - Table: Transactions +---------------+---------+ | Column Name | Type | +---------------+---------+ | id | int | | country | varchar | | state | enum | | amount | int | | trans_dat..

https://leetcode.com/problems/students-and-examinations/?envType=study-plan-v2&envId=top-sql-50 Students and Examinations - LeetCode Can you solve this real interview question? Students and Examinations - Table: Students +---------------+---------+ | Column Name | Type | +---------------+---------+ | student_id | int | | student_name | varchar | +---------------+---------+ student_id is leetcode..

https://leetcode.com/problems/confirmation-rate/?envType=study-plan-v2&envId=top-sql-50 Confirmation Rate - LeetCode Can you solve this real interview question? Confirmation Rate - Table: Signups +----------------+----------+ | Column Name | Type | +----------------+----------+ | user_id | int | | time_stamp | datetime | +----------------+----------+ user_id is the colum leetcode.com 처음에는 JOIN을 ..

https://leetcode.com/problems/average-time-of-process-per-machine/?envType=study-plan-v2&envId=top-sql-50 Average Time of Process per Machine - LeetCode Can you solve this real interview question? Average Time of Process per Machine - Table: Activity +----------------+---------+ | Column Name | Type | +----------------+---------+ | machine_id | int | | process_id | int | | activity_type | enum |..

https://leetcode.com/problems/customers-who-bought-all-products/description/?envType=study-plan-v2&envId=top-sql-50 Customers Who Bought All Products - LeetCode Can you solve this real interview question? Customers Who Bought All Products - Table: Customer +-------------+---------+ | Column Name | Type | +-------------+---------+ | customer_id | int | | product_key | int | +-------------+-------..

https://leetcode.com/problems/product-sales-analysis-iii/description/?envType=study-plan-v2&envId=top-sql-50 Product Sales Analysis III - LeetCode Can you solve this real interview question? Product Sales Analysis III - Level up your coding skills and quickly land a job. This is the best place to expand your knowledge and get prepared for your next interview. leetcode.com SELECT s.product_id, MI..

https://leetcode.com/problems/rising-temperature/description/?envType=study-plan-v2&envId=top-sql-50 recordDate를 기준으로 JOIN (a가 previous day가 되도록) SELECT b.Id FROM weather a INNER JOIN weather b ON a.recordDate = b.recordDate - 1 -- a : yesterday WHERE a.temperature < b.temperature LEFT JOIN이 아닌 INNER JOIN을 써줘야 연속된 날짜를 구할 수 있다. DATE 계산을 조금 더 깔끔하게 적으면 이렇게 적을 수도 있다 ! SELECT w2.id FROM Weather w1 JO..

하루에 5문제 이상씩 풀 예정 # 1757. Recyclable and Low Fat Products https://leetcode.com/problems/recyclable-and-low-fat-products/?envType=study-plan-v2&envId=top-sql-50 Recyclable and Low Fat Products - LeetCode Can you solve this real interview question? Recyclable and Low Fat Products - Table: Products +-------------+---------+ | Column Name | Type | +-------------+---------+ | product_id | int | | low_..

https://leetcode.com/problems/department-highest-salary/ LeetCode - The World's Leading Online Programming Learning Platform Level up your coding skills and quickly land a job. This is the best place to expand your knowledge and get prepared for your next interview. leetcode.com SELECT d.name AS department, e.name AS Employee, e.salary AS Salary FROM employee e LEFT JOIN department d ON e.depart..

https://www.hackerrank.com/challenges/earnings-of-employees/problem?h_r=internal-search&isFullScreen=true 1. WHERE절 서브쿼리 이용 earnings의 가장 큰 값을 구한 후 WHERE절을 이용해서 그 값을 가진 사람 수를 필터링 SELECT salary * months AS earnings, COUNT(*) FROM employee WHERE salary * months = ( SELECT MAX(salary*months) FROM employee ) -- WHERE 절에서 서브쿼리를 쓰고싶을때는 AS 로 불러올수가없다 ... GROUP BY earnings 2. HAVING절 서브쿼리 이용 1번과 차이는 GROUP..