2011

■ Edit joined data. (page 517)
■ Export data from the Data Table. (page 520)
Creating a Join
A join adds the properties from a data table (secondary table) to an existing
Feature Class layer (primary table). The original data remains unchanged in
its source—the join exists only within your map.
The secondary table can be an actual table, such as a named range in an Excel
spreadsheet, or the tabular data contained in a feature source, such as an Oracle
database or an SDF file.
NOTE Joins are available for geospatial data only, and not for drawing objects.
To join attribute data to drawing objects, see
Overview of Linking Database Records
to Objects
(page 522).
One-to-One Joins
The most common type of join is a one-to-one join, in which one feature is
matched to one secondary record, and any additional secondary records are
ignored. For example, if you are joining a table of income data to a layer
representing parcels, you may have more than one income value for a particular
property (if there are multiple residences on that parcel, for instance, or
multiple earners in a residence). In a one-to-one join, the first income value
found for a parcel is matched to that parcel, and any other income information
is ignored.
One-to-Many Joins
You can also create a one-to-many join. In this case, when there are multiple
secondary records for a single feature, additional features are generated to
represent the extra values. Using the same example as above, a parcel that
matches multiple income values will result in multiple Data Table entries for
that parcel, each with a separate income value (even though there is still only
one actual feature). If you style the parcel layer based on income values, only
one is visible in your display map. You can still edit the feature in your map
(for example, to resize it). The real feature in your data will be updated.
NOTE Adding features to your map can have performance implications; some
operations take longer when there is more feature data.
Creating a Join | 509