Among the users that permit the company to send regular emails to them, how many of them had made a transaction with a Visa card in July, 2014?
users permit the company to send regular emails to them refers to subscribedtoemaillist = 'TRUE'; Visa card refers to creditcardtype = 'Visa'; in July, 2014 refers to SUBSTR(TransactionDate, 1, 4) = '2014' AND SUBSTR(TransactionDate, 6, 2) = '07';
SELECT COUNT(T1.CustomerID) FROM customers AS T1 INNER JOIN `transaction` AS T2 ON T1.CustomerID = T2.CustomerID WHERE T1.SubscribedToEmailList = 'TRUE' AND T2.CreditCardType = 'Visa' AND STRFTIME('%Y-%m', T2.TransactionDate) = '2014-07'