Data Accessor is also known as Data Access Object [Alur 2001] and Logical Connection.
A data accessor implementation is an instance of Adapter [Gamma 1995] since it adapts an abstraction that is convenient for application usage to a particular physical database driver.
Singleton [Gamma 1995] and Abstract Factory [Gamma 1995] describe strategies for isolating a data accessor instantiation within a single component that is conveniently accessible throughout an application.
[Marinescu 2002] and [Matena 2003] describe an alternate approach to encapsulating physical data access operations called Data Access Command Beans. Data Access Command Beans define logical database operations using Command [Gamma 1995] semantics.
Consider using Data Accessor to abstract the data access portion of an Active Domain Object (33) or Object/Relational Map (53).
One or more data accessor abstractions can make up layers, as described in Layers (75). You can also define multiple data accessor abstractions for different layers. Each abstraction might address a different aspect or level of data access functionality.
