An enterprise business intelligence system includes a data access service. In one example, a method comprises receiving, with a data access service, a query and a report specification from an application, wherein the data access service is positioned between the application and a data source; creating a run tree that comprises a sequence of executable decoration nodes; executing the query on the data source, thereby providing a query result set comprising query results drawn from the data source that are responsive to the query; and executing the sequence of decoration nodes on the query result set. The decoration nodes modify the query result set, thereby producing a decorated result set based on the query result set and the decoration nodes. Producing the decorated result set comprises associating members or values in the query results with corresponding positions or calculated members in the report specification.