Database: book_publishing_company
Question: For the quantities, what percent more did the store in Fremont sell than the store in Portland in 1993?
SQL: SELECT CAST(SUM(CASE WHEN T2.city = 'Fremont' THEN qty END) - SUM(CASE WHEN T2.city = 'Portland' THEN qty END) AS REAL) * 100 / SUM(CASE WHEN T2.city = 'Fremont' THEN qty END) FROM sales AS T1 INNER JOIN stores AS T2 ON T1.stor_id = T2.stor_id WHERE STRFTIME('%Y', T1.ord_date) = '1993'