Re: JDBC

Marcelo Pereira wrote:

>Would you send to me a really simple example java source code using jdbc,
>acessing a simple table at PostgreSQL
>

Giving credit where credit is due, this is Mark Liyanage's simple java
program, from www.entorpy.ch.  It was written for OS X, but there
shouldn't be a problem.

/*
 * TestPostgreSQL.java
 *
 *
 * History:
 *
 * When         Who               What
 * ==============================================================================
 * 2001-06-23   Marc Liyanage     First version
 *
 *
 * License:
 *
 * Copyright abandoned 2001 by Marc Liyanage
 * Do with this whatever you want.
 *
 */

import java.sql.*;

/**
 * The TestPostgreSQL class shows how to access the PostgreSQL
 * DB server on Mac OS X using the JDBC interface.
 * It assumes the installation has been performed according
 * to the instructions at http://www.entropy.ch/software/macosx/postgresql.
 *
 *
 * You compile it like this:
 *
 *   % javac TestPostgreSQL.java
 *
 * Make sure that the PostgreSQL server has been
 * started with the -i flag. This is not the case in
 * the example lines of the installation instructions mentioned
 * above and in the StartupItem package that's available
 * from the same location. The -i flag tells the DB server
 * to listen for connection requests from the network
 * and I have left it off by default for security reasons.
 *
 * If the server is running correctly (with -i), run the Test like this:
 * (in the same directory where you compiled the example)
 *
 *   % java -classpath /usr/local/pgsql/share/java/postgresql.jar:. TestPostgreSQL
 *
 * You should see the current date as returned by the DB server:
 *
 *   2001-06-23 16:31:49+02
 *
 *
 * @author   Marc Liyanage
 * @version  1.0
 */
public class TestPostgreSQL {


    public static void main(String argv[]) throws Exception {

        // Load the driver class
        //
        Class.forName("org.postgresql.Driver");

        // Try to connect to the DB server.
        // We tell JDBC to use the "postgresql" driver
        // and to connect to the "template1" database
        // which should always exist in PostgreSQL.
        // We use the username "postgres" and no
        // password to connect. Since we're not accessing
        // any tables but only an SQL function
        // this should work.
        //
        Connection conn = DriverManager.getConnection(
            "jdbc:postgresql:template1",
            "postgres",
            ""
        );

        // Set up and run a query that fetches
        // the current date using the "now()" PostgreSQL function.
        //
        Statement stmt = conn.createStatement();
        ResultSet rset = stmt.executeQuery("SELECT now();");

        // Iterate through the rows of the result set
        // (obviously only one row in this example) and
        // print each one.
        //
        while (rset.next()) {
            System.out.println(rset.getString(1));
        }

        // Close result set, statement and DB connection
        //
        rset.close();
        stmt.close();
        conn.close();

    }


}