Practical PostgreSQL

Using JDBC

This section will be a brief introduction to JDBC, addressing the basics of JDBC, issues, caveats, and so forth. For more detailed information, visit the JDBC website (http://java.sun.com/products/jdbc/), which has many good resources and will always provide the most up to date information. Also, the API documentation included with your JDK has detailed information on specific classes, methods, and fields. Look for the java.sql package.

JDBC has classes to represent most of the basic pieces of a program’s interaction with SQL. The classes are: Connection, Statement, ResultSet, Blob, and Clob, and they all map directly to some concept in SQL. JDBC also has helper classes, such as ResultSetMetaData and DatabaseMetaData, that represent meta-information. These are useful for when you’d like to get information about the capabilities of the database. They are also useful for getting the types of results returned by a query, either for debugging, or because you don’t know about the data you are dealing with.

PostgreSQL’s JDBC interface also provides classes to map to PostgreSQL’s non-standard extensions to JDBC’s SQL support. These non-standard extensions include: Fastpath, geometric types, native large objects, and a class that aids serialization of Java objects into the database.

Basic JDBC Usage

Example 12-2 used a Connection object, representing a physical connection to the database. You can use this Connection object to create Statement objects. Statement objects are JDBC’s ...