I have a query that needs to build a display name for a field as part of the select list. The display name will consist of two database fields from the tables in the query. The first field will always be displayed. But the second field could potentially be null. If the second field is null then I just want to display the first field. But if the second field is not null then I want to display the first field a colon and then the second field and have it returned as part of the select list.