Using SharePoint 2013 Enterprise.

I have an external content type that I want to add a CBE Custom Action to which will allow me
to edit the selected item in an external web app running on a different server. I want this
Custom Action to redirect me to this external web app passing the item id in the querystring
(The data source is housed in a SQL server database and the item has it's own id assigned by
SQL server).

I have gotten to the point that I can get the item id (which is assigned by SharePoint) but
what I need is the id that is assigned by SQL Server which is within the item data.

Below is what I have so far for the Custom Action and it is returning the correct SharePoint
assigned id, but I cannot figure out how to get the real item data.
 

RegistrationId="{5feff46d-031c-4df5-ab06-27c25edfefb1}"
ImageUrl="" Location="EditControlBlock" Sequence="1001"
Description="Edit this SA"
Title="Edit Item">


RegistrationId="{5feff46d-031c-4df5-ab06-27c25edfefb1}"
ImageUrl="" Location="EditControlBlock" Sequence="1002"
Description="Delete this SA"
Title="Delete Item">


 
 If there is a better way to do this, please tell me. I am relativly new to SharePoint and
I thought this would be easy to do. But after 2 and a half days working solely on this one problem,
I still have not found a way to do it. I tried everything I could find on the internet and nothing
has worked.

Thanks in advance for any help/insight someone might provide.