SelectQuery sel = OQL

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

  .From(NW.Order)

  .Where(NW.Order.EmployeeID == 5)

  .GroupBy(NW.Order.CustomerID)

  .Having(OqlAggregate.Min(NW.Order.Freight) >= 100);

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

SELECT Max([Orders].[Freight])

FROM [Orders]

WHERE

  [Orders].[EmployeeID] = 5

GROUP BY [Orders].[CustomerID]

  HAVING

    Min([Orders].[Freight]) >= 100