7.3. Attribute Tables

To clearly separate between both types of tables (data and attribute), Thuban provides functionality regarding the attribute tables under the Layer menu.

7.3.1. Show Table

Layer->Show Table opens the attribute table of the currently active layer in a table view. In addition to the functionality described above selections affect also the map display: objects related to selected records are highlighted.

7.3.2. Join Table

Unlike the join described above, the join does not result in a new table. The attribute table of the currently active layer is the left table and other tables are joined to this table. The results of the join are available for classification. As a consequence, the join cannot result in fewer records than the source attribute table. The user is warned if the right table does not fulfill this constraint. An outer join must be used in such cases.

7.3.3. Unjoin Table

As said above, a normal table cannot be closed while it is still used in a join. While the joined table resulting from a join of normal tables can be simply closed (and thereby dereferencing the source tables), this is not possible for attribute tables. Hence joins on attribute tables must be solved explicitly. This is what the Layer->Unjoin Table item is used for: The last join for the currently active layer is solved.