I was trying to create an external list in sharepoint 2010 and i was getting this error: "Access Denied by Business Data Connectivity" when i am trying to view the external list in my sharepoint 2010 site.
The fix for this problem is easy since the cause of this error is : The business data connectivity service is not configured in sharepoint- permissions are not set !
What we will do is to configure the BDC service by set the security permissions on it:
1) open central administrations.
2) select application management.
3) select business data connectivity service.
4) Hover on your application and select set permission from the menu.
5) Add users that will have the permissions to use this BDC Application and assign the required permissions.
6) Click Ok.
Refresh the external list and will works :)
Hope this helps.