Retrieve records from the database based on a possible id

Question

This code will retrieve all records from the database if the id is null or return records by the available id. Is there a way to combine the query instead of having two separate queries?

// retrieve standard orders
let retrieveStdOrders id = 

    if id = null then
        query{
            for row in tool.db.Order_Order_StandardOrder do
            select {
                Id = row.Id;
                BusinessLocationId = row.BusinessLocationId;
                ProductOptionId = row.ProductOptionId;

            }
        }
    else
        query{
            for row in tool.db.Order_Order_StandardOrder do
            where(row.Id = id)
            select {
                Id = row.Id;
                BusinessLocationId = row.BusinessLocationId;
                ProductOptionId = row.ProductOptionId;

            }
        }