Accessing and managing external data in SharePoint is a hot topic since latest implementation of SharePoint. One of the really good tools available is BDC. However it comes with a number of challenges starting with complex configuration when setting up a BDC connection; there was also a limitation to read-only the data exposed by BDC. SharePoint 2010 takes the concept of BDC to the next level. You can treat your external data as a list with most of the operations available to lists and of course read, write, and modify your data.
We`ll start by opening your SharePoint site from your SharePoint Designer.
Once we have the site, we can create an external content type. Concept of content types is widely used to describe data entities within SharePoint such as links, items, announcements etc. Well now there is a content type for external data. Let’s go ahead and create one:
1. Select External Content Types
2. Pick New content type
3. Give your content type a name and click on a link to discover external data sources
4. If this is your first time connecting to the data source click Add a Connection 
and select SQL Server
5. Choose a server and a database as well as authentication
Now that we have a connection we need to create what’s called operations that will handle view, edit and delete from our SQL table.
Its really up to you if you’re going to create all 4 operations or some of them or whether you let SharePoint designer create those operations using default access or maybe you will reuse your own stored procedure of function for some of the operations. In our example we’ll let SPD handle the creation of all the default operations. Its worth mentioning here that created operations won’t be placed in your source database and schema of your database should not be altered.
Below i select a table I want to connect to and generate list of operations:
Once you have your operations, you can save your content type.
Your content type is ready to be used in an external list now.
Here is how to create one from a lists section External List command
Once you select a content type of your choice, and a list name your external list will be created:
Now that the list is created you can treat the data in your list as in any other list.
You’ll notice that workflows and some other features will not be enabled on the list; mainly because this external list lacks some of the properties, such as pushing events based on actions being executed in underlying data store.
Hope this article will get you a quick start on what's out there in external data management in SharePoint 2010.
Yaroslav Pentsarskyy, Microsoft SharePoint MVP
Blog: www.sharemuch.com
