Table joins have been on our wish list for quite a while. After all, it is much nicer to add a join than to go through the process of creating a new shapefile with joined attribute table using “Join by Attributes”.
The time has come!
Users of QGIS trunk may have already noticed the new “Joins” tab in Layer Properties:
The join results in an extended attribute table. If there is no matching row in the joined table, the attributes will be set to NULL.