Re: [GENERAL] 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@pereira.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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