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Author: letsdeepchat

BASIC JOIN/1068. Product Sales Analysis I.sql

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+# Write your MySQL query statement below
+SELECT p.product_name, s.year, s.price
+FROM Sales s LEFT JOIN Product p ON s.product_id = p.product_id;

BASIC JOIN/1378. Replace Employee ID With The Unique Identifier.sql

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+# Write your MySQL query statement below
+SELECT eu.unique_id AS unique_id, e.name AS name
+FROM Employees e LEFT JOIN EmployeeUNI eu ON e.id = eu.id;

BASIC JOIN/1581. Customer Who Visited but Did Not Make Any Transactions.sql

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+# Write your MySQL query statement below
+SELECT v.customer_id, COUNT(v.visit_id) AS count_no_trans
+FROM Visits v LEFT JOIN Transactions t 
+ON v.visit_id = t.visit_id
+WHERE t.transaction_id IS NULL
+GROUP BY v.customer_id;

SELECT/1148. Article Views I.sql

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+# Write your MySQL query statement below
+SELECT DISTINCT author_id as id from Views
+WHERE author_id = viewer_id
+ORDER BY id;

SELECT/1683. Invalid Tweets.sql

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+# Write your MySQL query statement below
+SELECT tweet_id FROM Tweets WHERE length(content) > 15;

SELECT/1757. Recyclable and Low Fat Products.sql

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+# Write your MySQL query statement below
+SELECT product_id 
+FROM Products
+WHERE low_fats = 'Y' 
+AND recyclable = 'Y';

SELECT/584. Find Customer Referee.sql

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+-- Write your PostgreSQL query statement below
+SELECT name from Customer
+WHERE referee_id is null or referee_id != 2;

SELECT/595. Big Countries.sql

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+# Write your MySQL query statement below
+SELECT name, population, area
+FROM World
+WHERE area >= 3000000 
+OR population >= 25000000;