Solutions for [SQL 50 Study Plan](https://leetcode.com/studyplan/top-sql-50/) on LeetCode

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 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 I

SELECT DISTINCT author_id as id

FROM Views

WHERE viewer_id >= 1

AND 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 unique_id, name

FROM Employees e

LEFT JOIN EmployeeUNI eu

ON e.id = eu.id

1068 - Product Sales Analysis I

SELECT product_name, year, price

FROM Sales s

LEFT JOIN Product p

ON s.product_id = p.product_id

1581 - Customer Who Visited but Did Not Make Any Transactions

SELECT customer_id, COUNT(*) as count_no_trans

FROM Visits

WHERE visit_id NOT IN (SELECT DISTINCT visit_id FROM Transactions)

GROUP BY customer_id