Question regarding adding UIDs to a geodatabase

[KathleenBolger1]

This is a very basic question, but I'm just stumped. I'm a GIS student.

I'm being asked to create a unique ID in a database. There are five separate feature classes (five different states with geocoded data) within the file geodatabase. How do I create a UID for the whole thing? Or do I just create a field in each feature with UIDs and accept that each one will have overlapping UIDs?

Does this make any sense?

Thanks so much for any help you can give,

Kathy

[RexRobichaux2]

Hello Kathleen, 

  Thanks for posting up your question. The answer really depends upon what you need out of your potential UID / OID field. Generally speaking, if your data is currently in feature class / file geodatabase format chances are that your five feature classes already have OID (something like an OBJECTID field) fields as it's required by ArcGIS. That said, if they for some reason lack a unique identifier field, you have a few options, you can either copy and paste each feature class in the same file geodatabase which will create a copy with a new unique / OID field, or if you want a unique field in the form of a global ID, you can right click each feature class < Manage < Add Global IDs. 

  Keep in mind that if the records / rows in each feature class vary, their respective OID values will also vary accordingly. More information on OID fields can be found here: Fundamentals of ObjectID fields—Help | ArcGIS Desktop 

I hope this information is helpful! 

-Rex