Re: JDBC

Hi Jeffrey,

Thanks for your example code. I have compiled it without any problem, but
when I try to run I have the following:

$ javac TestPostgreSQL.java
$ java TestPostgreSQL.class
Exception in thread
"main" java.lang.NoClassDefFoundError: TestPostgreSQL/class

$ java -classpath
/usr/local/pgsql/share/java/postgresql.jar:. TestPostgreSQL.class
Exception in thread
"main" java.lang.NoClassDefFoundError: TestPostgreSQL/class

$ export CLASSPATH=/usr/local/pgsql/share/java/postgresql.jar:.
$ java TestPostgreSQL.class
Exception in thread
"main" java.lang.NoClassDefFoundError: TestPostgreSQL/class

As you can see I have this problem, whatever I try to do. So I thought my
JDBC driver wasn't properly compiled, so I have downloaded the 7.3 JDBC
driver from PostgreSQL.org (pg73jdbc1.jar) and run all the tests above,
always with the same problem.

What am I doing wrong??

Thanks in advance and
Best Regards,

Marcelo Pereira

-- Remember that only God and ^[:w saves.
__
(_.\ © Marcelo Pereira |
/ / ___ marcelo(at)pereira(dot)com |
/ (_/ _ \__ [Math|99]-IMECC |
_______\____/_\___)___Unicamp_______________/

--- Jeffrey Melloy, with his fast fingers, wrote:

:> 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();
:>
:> }
:>
:>
:> }
:>
:>
:>
:>
:>
:>
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:>
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