Using ArcMap 10.1.
Is this possible to have one polygon and join to a database/excel with many matching records?
I would like to have 1 polygon but match to 100 corresponding records in a table. When I use the identify tool or select this polygon all 100 matching records would display?
[GIS] One Polygon Joining to Database with Many matching records
attribute-joinsdatadatabasepolygonrelates
Related Solutions
It's sometimes confusing, but it's really a matter of perspective. See this diagram (from this topic) for a reference:
This is an example of five relationships (and three different cardinalities).
- One-to-many: Parcels are related to the ParcelToOwner table in a one-to-many relationship; one parcel may have many owners (partial ownership).
- Many-to-one: The ParcelToOwner table is related to Parcels in a many-to-one relationship; many owners own (at least some percentage of) a parcel.
- Many-to-one: The ParcelToOwner table is related to Owners in a many-to-one relationship; many parcels may be owned (at least partially) by one owner.
- One-to-many: Owners are related to the ParcelToOwner table in a one-to-many relationship; one owner may own many parcels (again, at least partially)
- Many-to-many: Parcels are related to Owners in a many-to-many relationship; many parcels may be (at least partially) owned by many owners, and many owners may own (at least partially) many parcels. This is expressed through the ParcelToOwner table and the aforementioned relationships. Most DBMSs cannot express a many-to-many relationship without an intermediary table (source), hence this design.
As you can see, whether a relationship is one-to-many or many-to-one depends on how you look at it.
All that being said, the easiest way to accomplish what you're looking for is to create a query table that creates many identical parcels, one for each mobile home. See this blog post for more details: A quick tip on performing a 1:M join
If all of your data is in an enterprise geodatabase, you could also use a Query Layer to do the same thing, on the fly (no intermediate feature class).
At ArcMap 10.1, for data in the same geodatabase, any time that you join two data sources together that have a 1:M relationship (two or more records match on the join field in the joined table) the full set of related records are expanded to complete all record combinations whenever the data is exported. So your join table has some duplicate values in the join field that match the same record in your primary table. This is a good behavior, since that is how Access and other databases deal with these relationships, and it exposes false assumptions that two data sources have a 1:1 relationship when in fact they have a 1:M relationship. Perform a summary on the join field in the join table and look for any values with a frequency of 2 or more.
For Spatial Joins the number of points should not expand unless you inputted a layer as the target that had a 1:M attribute join in place, or you chose the One To Many output option and had points that touched the boundary of two or more polygons/lines.
Best Answer
MakeQueryTable will perform a one-to-many join from polygon to a table. It only works on a geodatabase, no shapefile support. Also, your excel/database table must be copied to the same workspace as the polygon features. The tool output is a feature layer, so you will want to save to disk with Copyfeatures.