Create unpopular-books.sql

Author: kamyu104

MySQL/unpopular-books.sql

@@ -0,0 +1,12 @@
+# Time:  O(m + n)
+# Space: O(n)
+
+SELECT b.book_id, 
+       b.NAME 
+FROM   books AS b 
+       LEFT JOIN orders AS o 
+              ON b.book_id = o.book_id 
+                 AND dispatch_date BETWEEN '2018-06-23' AND '2019-6-23' 
+WHERE  Datediff('2019-06-23', b.available_from) > 30 
+GROUP BY book_id 
+HAVING Sum(IFNULL(o.quantity, 0)) < 10 ORDER  BY NULL