SelectQuery sel = OQL

  .Select(OqlAggregate.Sum(NW.Order.Freight))

  .From(NW.Order)

  .Where(NW.Order.EmployeeID == 5

    & (NW.Order.ShipVia == 1 | NW.Order.EmployeeID == 5)

    & NW.Order.ShipVia == 1

    & NW.Order.ShipAddress.Like("NW%")

    & (NW.Order.ShipAddress + "abc").Like("abc%abc")

  )

  .GroupBy(NW.Order.CustomerID);

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

SELECT Sum([Orders].[Freight])

FROM [Orders]

WHERE

  [Orders].[EmployeeID] = 5 AND

  (

    [Orders].[ShipVia] = 1 OR

    [Orders].[EmployeeID] = 5

  ) AND

  [Orders].[ShipVia] = 1 AND

  [Orders].[ShipAddress] LIKE 'NW%' AND

  [Orders].[ShipAddress] + 'abc' LIKE 'abc%abc'

GROUP BY [Orders].[CustomerID]