-- Database schema
| Customers : CustomerID [ INTEGER ] primary_key , Customer Names [ TEXT ] | Products : ProductID [ INTEGER ] primary_key , Product Name [ TEXT ] | Regions : StateCode [ TEXT ] primary_key , State [ TEXT ] , Region [ TEXT ] | Sales Team : SalesTeamID [ INTEGER ] primary_key , Sales Team [ TEXT ] , Region [ TEXT ] | Store Locations : StoreID [ INTEGER ] primary_key , City Name [ TEXT ] , County [ TEXT ] , StateCode [ TEXT ] Store Locations.StateCode = Regions.StateCode , State [ TEXT ] , Type [ TEXT ] , Latitude [ REAL ] , Longitude [ REAL ] , AreaCode [ INTEGER ] , Population [ INTEGER ] , Household Income [ INTEGER ] , Median Income [ INTEGER ] , Land Area [ INTEGER ] , Water Area [ INTEGER ] , Time Zone [ TEXT ] | Sales Orders : OrderNumber [ TEXT ] primary_key , Sales Channel [ TEXT ] , WarehouseCode [ TEXT ] , ProcuredDate [ TEXT ] , OrderDate [ TEXT ] , ShipDate [ TEXT ] , DeliveryDate [ TEXT ] , CurrencyCode [ TEXT ] , _SalesTeamID [ INTEGER ] Sales Orders._SalesTeamID = Sales Team.SalesTeamID , _CustomerID [ INTEGER ] Sales Orders._CustomerID = Customers.CustomerID , _StoreID [ INTEGER ] Sales Orders._StoreID = Store Locations.StoreID , _ProductID [ INTEGER ] Sales Orders._ProductID = Products.ProductID , Order Quantity [ INTEGER ] , Discount Applied [ REAL ] , Unit Price [ TEXT ] , Unit Cost [ TEXT ] |
-- -- State the order number where Qualitest ordered the highest product quantity.

SELECT T1.OrderNumber FROM `Sales Orders` AS T1 INNER JOIN Customers AS T2 ON T2.CustomerID = T1._CustomerID WHERE T2.`Customer Names` = 'Qualitest ' ORDER BY T1.`Order Quantity` DESC LIMIT 1;