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. Join Keys To be joined, the primary and secondary tables must contain matching fields with common values. These matching fields are the join keys.
A join key does not need to have the same name in both data sources, but it must have the same data type numeric, string, Boolean, and so on. Advanced Joining You can join multiple secondary tables to a feature layer There are several ways to do this. Open the map you created in Lesson 1: Prepare the Map. For example, if you named the map from lesson 1 MyMap. Create a copy of the map to use as a key map view. Save the map with a similar name to the original one. For example, if the original map is MyMap.
Close the map file and reopen the original one MyMap. You will use MyMapKeyView. Generate a legend that you can link to the Legend viewport. Switch the Task Pane to the Display Manager tab. Click Tools Create Legend. Click a blank space that is outside the bounding box of the mapped area.