Write SQL query to solve given problem: How many online sales were made in May 2018 where products were shipped from Norman?. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT SUM(CASE WHEN T1.OrderDate LIKE '5/%/18' AND T1.`Sales Channel` = 'Online' AND T2.`City Name` = 'Norman' THEN 1 ELSE 0 END) FROM `Sales Orders` AS T1 INNER JOIN `Store Locations` AS T2 ON T2.StoreID = T1._StoreID