QBE queries are expressed “by example.” Instead of giving a procedure for obtaining the desired answer, the user gives an example of what is desired. The system generalizes this example to compute the answer to the query. We express queries in QBE by skeleton tables. These tables show the relation schema, as in Figure 5.1. Rather than clutter the display with all skeletons, the user selects those skeletons needed for a given query and fills in the skeletons with example rows.