Hello Elias -
While we do not have an inbound connector available for retrieving data from an RDBMS table, we do have an out-of-the-box input Poll an ArcGIS Server for Features which will poll a feature service for features. This is perhaps a subtle distinction since, yes, a feature service is backed by a feature class whose data table is in an RDMBS ... but the feature service provides the interface we've developed the inbound connector to use.
I've attached an illustration of how you might configure this type of input. In the illustration, notice that I have specified the registered connection to my local ArcGIS for Server (RSUNDERMAN_AGS), the services folder (GEP_Forum), and the name of the feature service I want to poll (USGS_Earthquakes_LastHour). That feature service has a layer, also named USGS_Earthquakes_LastHour, which contains the features I will be polling.
I had previously imported a GeoEvent Definition from this feature service, so I specify that the input should not attempt to create one, but should instead use the one I imported named USGS_Earthquakes_LastHour. Evidently I wasn't feeling very creative with my names. 🙂
The Refresh Interval is expressed in seconds. So this input would poll the feature service every 10 seconds for data. The Get Incremental Updates parameter was changed at 10.2.1 to allow configuration based on timestamp (as shown) vs. OBJECTID (which is your only option at 10.2.0).
I've left the defaults beneath Advanced unchanged ... particularly the option to not delete features polled by GeoEvent Processor.
Please let us know if this input will do what you need.
[ATTACH=CONFIG]32882[/ATTACH]
Thanks -
RJ