They have introduced cool concept named Alternate Key in 2015 Update 1.
Alternate key can be used as a unique identifier for the record.
Why we need Alternate key as we already have primary key?
This will come handy when you are integrating CRM data with external databases which might deal with natural data type than GUID’S. Which will help developers to write integration code easily.
And also when we are working with external we may not have access to update external database tables to add unique identifier for referencing.With alternate keys you can now define an attribute in a CRM entity to correspond to a unique identifier used by the external data store.
This is how a Alternate key can be created from UI.
Alternate keys can be created only on the below data types.
- Decimal Number
Single line of text
Unfortunately Date/Time, Lookup and OptionSet fields cannot be used as the key fields in this release, which could be something that you might want to use sometimes.
You can alternatively use SDK to create CRM Alternate Keys. You will be looking at CreateEntityKeyRequest message if you ever want to do so.
For more information follow the below articles