SelectQuery qryCustomer = OQL

  .Select(NW.Customer.CustomerID)

  .From(NW.Customer)

  .Where(NW.Customer.ContactTitle == "Owner");

UpdateQuery updOrder = OQL

  .Update(NW.Order)

  .Set(NW.Order.ShippedDate, NW.Order.ShippedDate + 1)

    ._(NW.Order.Freight, NW.Order.Freight * 2)

  .Where(NW.Order.CustomerID.In(qryCustomer));

The SQL statements generated as follows (taking SQL Server as an example)

UPDATE

  [Orders]

SET

  [Orders].[ShippedDate] = [Orders].[ShippedDate] + 1 ,

  [Orders].[Freight] = [Orders].[Freight] * 2

WHERE

  [Orders].[CustomerID] IN

    (

      SELECT [Customers].[CustomerID]

      FROM [Customers]

      WHERE

        [Customers].[ContactTitle] = 'Owner'

    )