Обсуждение: How to access postgresql database using jdbc driver?

Hi Robson,

What are the errors? I suggest you to read the JDBC section in 
the java tutorial (on java.sun.com web site), there's also
code sample on: 
http://developer.java.sun.com/developer/codesamples/database/

For postresql specific issue concerning the JDBC driver you can
have a look at the "Postgresql Programmer's Guide" 
(doc/programmer.ps) and the example programs which are in the 
pgsql/src/interfaces/jdbc/example directory...

Regards,
Benoit

> Robson Martins wrote:
> 
> Hello all.
> My name is Robson.
> I'm starting on java language yet, and I'm having problems to access
> postgre sql database with jdbc.
> I have PostgreSQL 6.5, JDK1.1.8, and a jdbc driver to JDK1.1.x
> I'm using the comands:
>  Class.forName("postgresql.Driver"); -> to select the type of database
>  Connection db =
> DriverManager.getConnection("jdbc:postgresql://200.210.212.4:5432/imf",
> "username", "password"); -> to  connect to the database
> But i dont know how I check if worked, and I get a lot of errors.
> Anybody can send me a example .java that show me how to load the
> driver, connect to the database, see if worked, create tables, and
> others, using postgres 6.5?
> I didnt find on the web.
> Please anybody help me with this!
> I'm waiting any answer...
> Robson ( robson@netalfa.com.br )
> 
> 
> 

-- 
Benoit Foucher                                      mailto:benoit@ooc.com
Object-Oriented Concepts, Inc.  (trainee) 
44 Manning Road
Billerica, MA 01821

I'm attaching here a simple Java program that will open, create a table
and query the table printing the results!

yourdb database must be previously created!

Best regards,
--
Constantin Teodorescu
FLEX Consulting Braila, ROMANIAimport java.io.*;
import java.sql.*;

public class tutorial {

    private Connection dc;
    private Statement st;


    public tutorial() {
        try {
            Class.forName("postgresql.Driver");
        } catch (Exception e) {
            e.printStackTrace();
            System.out.println("Cannot load PostgreSQL driver\n"+e.getMessage());
            System.exit(-1);
        }
    }

    public boolean openDatabase() {
        boolean result;
        try {
            dc = DriverManager.getConnection("jdbc:postgresql://localhost/yourdb","yourname","yourpassword");
            st = dc.createStatement();
            result = true;
        } catch (Exception e) {
            e.printStackTrace();
            System.out.println("Cannot connect to database\nError:"+e.getMessage());
            result = false;
        }
        return result;
    }

    public void run() {
        System.out.println("Starting work!");
        try {
            st.executeUpdate("create table people (id int4, name varchar(32))");
            st.executeUpdate("insert into people values(1,'teo')");
            st.executeUpdate("insert into people values(2,'peter')");
            ResultSet rs = st.executeQuery("select id,name from people");
            if ( rs != null) {
                while ( rs.next() ) {
                    System.out.println(rs.getString("name")+" has id= "+rs.getString("id"));
                }
                rs.close();
            }
            st.executeUpdate("drop table people");
        } catch (SQLException sqle) {
            System.out.println("A SQL exception occured : "+sqle.getMessage());
        }
        System.out.println("Finished!");
    }

    public static void main(String argv[]) {
        tutorial task = new tutorial();
        if ( task.openDatabase() ) task.run();
    }
}