This post talks about enterprise library data access block. I was able to go over the documentation on the msdn. Applications that have been using custom connection state and pooling as well as connections usually run into scalability and resource problems. The enterprise library opens and closes the connection as needed leaving you to focus on the dataReader and the data. You can edit the configuration with a visual tool. A database object is created using the DatabaseFactory.CreateDatabase method. The configuration tool stores the settings in the DAAB ( Data Access Application Block). The databases instances node is used to associate one of the instances type such as SQL or Oracle with one of the connection strings.  The connection string is stored in the configuration file and provides mechanisms to configure the security for the connection.  These can be encrypted so that they are not in clear text. As mentioned the database node is created first and this is done with a factory pattern. In ADO.Net, you open a connection, then fill a dataset or retrieve data through a data reader usually typed to the provider. In this application block, all of these are abstracted.  You just instantiate the database object and execute the reader using a command wrapper. This Database class has dozens of methods  most notably the ones to execute a stored procedure or SQL statement, return a dataset, a datareader, a scalar value, an xmlreader or nothing, allow for specific parameters to be created and passed in, determine which parameters that it needs, creates them and caches them, and involves commands in transaction.
The database object has some methods like the GetStoredProcCommand, GetParameterValue, AddInParameter, AddOutParameter that give detailed control over the database object
to be executed.  ExecuteScalar and ExecuteReader are some of the methods for execution. Since the results from the execution can be read from a dataReader, we can
directly populate objects with the results without having to create an object graph. This reduces a lot of complexity that comes with the object graph refreshes. Direct
manipulation of data is possible with methods like LoadDataSet and UpdateDataSet where you can specify the CRUD operation command and a transaction if necessary. You
could directly get the data adapter that implements the CRUD operation on the data source.