Entity beans represent shared persistent data stored in an RDBMS or other persistent data store. If the data store is relational, the responsibility for actually performing the JDBC can be placed either with the bean itself or with the EJB container.
The term for the former is bean-managed persistence (BMP), and for the latter it is container-managed persistence (CMP).
The EJB specification is very much oriented around relational data stores. Certainly, container-managed persistence can only be performed through JDBC javax.sql.DataSource objects, and JDBC is based around ANSI SQL 92.
If using bean-managed persistence, any API can be used to save the bean's state to a persistent data store, but even then, the methods that ...