The user can calculate and update database with layer area.
Select the layer in the Layer Explorer and click with mouse right button.
Click on CALCULATE AREA...
Layer: presents the selected layer name.
SRS:
click on this box if layer projection is to be used, otherwise
unselect the box and click on button
to change the layer projection.
Area Unit: select the wanted unit.
Create Column Area: enter the name of the column.
Click on Calculate button.
Results will be presented in the interface.