fixed top_ten_borrowed_books view, should use count instead of sum

Author: wenjie-mdb

docker/sample-postgres-library/init/1-library-schema-and-data.sql

@@ -88814,11 +88814,11 @@ CREATE OR REPLACE VIEW library.top_ten_borrowed_books AS
     books.pages,
     books.year,
     books.publisher,
-    sum(issue_details.id) AS issue_count
+    COUNT(issue_details.id) AS issue_count
    FROM (library.books
      JOIN library.issue_details ON (((books.id)::text = (issue_details.book_id)::text)))
   GROUP BY books.id
-  ORDER BY (sum(issue_details.id)) DESC
+  ORDER BY issue_count DESC
  LIMIT 10;