| As a technology, JDO complements the JDBC API. It is an interface used for storing Java data objects into a data store. It provides an API for transparent database access. Using JDO, you can retrieve data on the application end right away, manipulate it locally, and then persist it to the database. It has been designed to be layered on top of the JDBC and SQL relational database technologies, so that the programmer can use the Java programming language to develop database-language-independent code. This technology also offers query facilities that can query from the Java object model of your application. JDO also provides a standard Java Interface to support Object Relational Mapping. JDBC 3.0 is the new JDBC API, based on the already existing JDBC API. This new set of specifications has the following enhancements: New Interfaces, namely the DatabaseMetaData interface that retrieves the SQL type hierarchies, and the ParameterMetaData interface that describes properties of parameters in PreparedStatement objects. In the earlier JDBC API, in order to set a parameter in a stored procedure, the param-eter had to be accessed by its position index, and not by its name. The JDBC 3.0 API provides added functions to access these parameters by their names as well. In addition to updating the ResultSet interface to support updating CLOB, BLOB, and ARRAY data types, two new data types have been added. The two new data types are java.sql.Types.DATALINK, which provides access to external resources or URLs (value obtained from ResultSet using the getURL() method, which is analogous to the getString(), getInt(), and so on methods), and java.sql.Types.BOOLEAN, which is logically similar to the BIT type, and obtains from the ResultSet using the getBoolean() method. To obtain the value of the key generated on inserts into tables containing columns with default values as sequences, JDBC 3.0 API has introduced a new flag called Statement.RETURN_GENERATED_KEYS and Statement.NO_GENERATED_KEYS. This flag is introduced into the Insert statement at the position of the value to be inserted into the column. Above and beyond these main features, JDBC 3.0 also introduces connection pooling, prepared statement pooling, savepoints in transactions, multiple ResultSet returns, and ResultSet holdability-related API. WebLogic supports JDK1.3.1, which supports JDBC 2.0 API. |
