[Leetcode] SQL50 문제 (MYSQL)

1757. Recyclable and Low Fat Products

SELECT product_id
FROM Products
WHERE low_fats = 'Y' AND recyclable = 'Y';

 

 

584. Find Customer Referee

SELECT name
FROM Customer
WHERE NOT referee_id = 2 OR referee_id IS NULL;

 

 

595. Big Countries

SELECT name, population, area
FROM World
WHERE area >= 3000000 OR population >= 25000000;

 

 

1148. Article Views 1

SELECT DISTINCT author_id AS id
FROM Views
WHERE author_id = viewer_id
ORDER BY author_id;

 

 

1683. Invalid Tweets

SELECT tweet_id
FROM Tweets
WHERE LENGTH(content) > 15;

 

 

1378. Replace Employee Id With The Unique Identifier

SELECT B.unique_id, A.name
FROM Employees A LEFT JOIN EmployeeUNI B ON A.id = B.id;

 

 

1068. Product Sales Analysis 1

SELECT b.product_name, a.year, a.price
FROM Sales a JOIN Product b ON a.product_id = b.product_id;

 

 

1581. Customer Who Visited but Did Not Make Any Transactions

SELECT a.customer_id, COUNT(a.customer_id) AS count_no_trans
FROM Visits a LEFT JOIN Transactions b ON a.visit_id = b.visit_id
WHERE b.visit_id IS NULL
GROUP BY a.customer_id;