A computer displays data sources associated with tables of data. The computer also displays a tree of data object icons, each representing a logical combination of tables. While displaying the data sources and the data object icons, the computer detects a portion of an input on a candidate data object icon. In response, the computer determines linking fields corresponding to a neighboring data object icon and linking fields corresponding to the candidate object icon. The computer displays options for a user to select linking fields. In response to detecting selection of linking fields, the computer validates the selection and/or updates the tree of data object icons based on the selected linking fields.