data > Data types > Feature datasets > An overview of working with feature datasets
Associating features and records
In some cases, you may want to associate features or records in one dataset with features or records in another. With ArcGIS, you can make associations using table joins and relates, relationship classes, and spatial joins. Table joins, relates, and relationship classes use a common field, known as a key, to associate records in one table with records in another table. ArcGIS supports one-to-one, one-to-many, many-to-one, and many-to-many relationships, making it easy to associate tables regardless of the nature of your data. If your data lacks a common key field, you can use a spatial join to create a relationship that is based on the location of features in your input layers.
Joins and relates are most useful when you need to create temporary associations. With a table join, the attributes from one table are virtually appended to the attributes of another table. After the join is established, you can use the information from the appended table for symbology, field calculation, and more. For example, you could associate a table of soil sample values to a land parcels layer based on a shared parcel ID field. After this association is made, you can symbolize the land parcels layer based on the soil sample values in the soil samples table. Joined tables can be exported to preserve the join in a new feature class or nonspatial table, or they can be removed if they are no longer needed. Relates allow you to identify a record in one table and see all the related records from a related table. Unlike a table join, a relate defines a relationship, but it does not append the attributes of one table to the other. Rather, it allows you to access related information by selecting features or records in your layer or table using the Explore tool in ArcGIS Pro or the Identify tool in ArcMap.
If you want to create a more permanent association, you can use a relationship class. Relationship classes are stored in a geodatabase, making them accessible to anyone using the geodatabase. They can be used to enforce referential integrity between related objects (so that when one object is modified, the related object is updated automatically), and they support all cardinalities. ArcGIS supports both simple and composite relationship classes. In a simple relationship class, the related objects are loosely coupled. For example, when you delete a record in the origin table, the key field in the destination record is nulled. You should use simple relationship classes when you have related objects that are completely independent of one another. Conversely, you should use a composite relationship class when working with related objects that cannot exist independently. In a composite relationship class, when one object is deleted, the second object (a related object) is also deleted. This approach can save you time that might otherwise be spent performing attribute edits.
Prepare
These topics in the documentation provide details about associating features and records.
Gain a thorough understanding of these ArcGIS Pro Help topics:
Help > Data > Data types > Tables > Joins and relates (and all subtopics)
Help > Data > Data types > Relationship classes (and all subtopics)
Gain a thorough understanding of these ArcMap Help topics:
Manage data > Data types > Relationships and related objects (and all subtopics)
Manage data > Data types > Tables > Joining tables by spatial query (and all subtopics)
Topology
Topology is a collection of rules and relationships that define the coincidence between point, line, and polygon features. You can create a topology to preserve the spatial relationships between features in your data. You can also use topology tools to validate and fix any potential errors. Topology includes rules that help ensure data quality; for example, you can set topology rules that will help you minimize gaps or overlaps among coincident features or simultaneously edit features that overlap or touch.
Two types of topology are supported in ArcGIS: map topology and geodatabase topology. Map topology is available at all license levels, whereas geodatabase topology requires an ArcGIS Standard or Advanced license. Map topology does not require any setup and can be used to maintain the coincidence, covering, and crossing of any visible features in your maps. Geodatabase topology is stored as part of a feature dataset and includes a collection of rules and editing tools that enable your geodatabase to accurately model the geometric relationships between features in one or more of the participating feature classes.
ArcGIS includes geoprocessing tools that you can use to build, analyze, manage, and validate topologies. For example, you can use tools in the Topology toolset to build and load data into a topology. Then you can define rules to edit and maintain the participating features. Once these rules are in place, you can run a validation against the topology, and ArcGIS will identify areas that require edits or that have broken your rules. If a predefined fix is available, you can quickly fix the error using functionality in the user interface; if not, you can modify the features using modify tools and can validate the areas again to ensure that your changes have fixed the error.
Prepare
These topics in the documentation provide details about topology.
Gain a thorough understanding of these ArcGIS Pro Help topics:
Help > Data > Edit geographic data > Modify topology >Introduction to editing topologyMap topologyGeodatabase topology (and all subtopics)
Gain a thorough understanding of these ArcMap Help topics:
Manage data > Data types > Topologies (and all subtopics)
Practice
Take these web courses to get more hands-on experience:
