Difference between revisions of "JDBC and MySQL"

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[[Category:HOWTOs (English)]]
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[[Category:Development]]
[[Category:Development (English)]]
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=Introduction=
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This document describes how to set up your Arch system so MySQL Databases can be accessed via Java programs.
 
This document describes how to set up your Arch system so MySQL Databases can be accessed via Java programs.
  
=Installation=
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== Installation ==
  
==Installing MySQL==
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===Installing MySQL===
  
To start with, switch to the system user, then install MySQL.
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[[pacman|install]] package {{pkg|mysql}} available in the [[Official Repositories]].
  
su (enter your system password)
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There are now two "fixes" you have to make. Firstly edit the file {{ic|/etc/mysql/my.cnf}} to allow network access. Find the line with skip_networking in and comment it out so it looks like this
pacman -S mysql
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There are now two "fixes" you have to make. Firstly edit the file my.conf to allow network access
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gedit /etc/my.cnf
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Find the line with skip_networking in and comment it out so it looks like this
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  #skip-networking
 
  #skip-networking
 
Close that file, and edit the /etc/hosts.allow file
 
 
gedit /etc/hosts.allow
 
 
and enter on a blank line
 
 
mysqld : ALL : ACCEPT
 
  
 
Finally start mysql up with :
 
Finally start mysql up with :
  
  /etc/rc.d/mysqld start
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  # /etc/rc.d/mysqld start
  
==Installing JDBC==
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===Installing JDBC===
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JDBC [[PKGBUILD]] is currently in [[AUR]] repository.
  
JDBC is not currently in the repositories. I downloaded the current version, at the time of writing 5.06 from the MySQL website at http://www.mysql.com/products/connector-j/
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You can also download it from http://www.mysql.com/products/connector-j/ and
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( x=mysql-connector-java-*-bin.jar; install -D $x /opt/java/jre/lib/ext/${x##*/} )
  
Next, unpack it into a temporary directory
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==Testing==
 
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cd /tmp
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tar xzvf /aux/arch/extras/mysql-connector-java-5.0.6.tar.gz (the exact filename will depend on where you download it to)
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Finally, copy it into the java extensions directory
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  cp mysql-connector-java-5.0.6-bin.jar /opt/java/jre/lib/ext/
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JDBC [[PKGBUILD]] is currently in [[AUR]] repository. Use [[yaourt]] to install it:
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yaourt -Sy mysql-jdbc
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=Testing=
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To access mysql's command line tool,  
 
To access mysql's command line tool,  
  
  mysql
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  $ mysql
 
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==Creating the test database==
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===Creating the test database===
  
 
The following commands create a database and allow a user 'paulr'. You will need to change the user name to whatever yours is.
 
The following commands create a database and allow a user 'paulr'. You will need to change the user name to whatever yours is.
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Now press Ctrl+D to exit the command line tool.
 
Now press Ctrl+D to exit the command line tool.
  
==Creating the test program==
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===Creating the test program===
  
 
Use an editor to create a file DBDemo.java with the following code in it. You will need to change the username and password appropriately.
 
Use an editor to create a file DBDemo.java with the following code in it. You will need to change the username and password appropriately.
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  }
 
  }
  
==Running the Program==
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===Running the Program===
  
 
To compile and run the program enter
 
To compile and run the program enter

Revision as of 21:11, 23 August 2012

This document describes how to set up your Arch system so MySQL Databases can be accessed via Java programs.

Installation

Installing MySQL

install package mysql available in the Official Repositories.

There are now two "fixes" you have to make. Firstly edit the file /etc/mysql/my.cnf to allow network access. Find the line with skip_networking in and comment it out so it looks like this

#skip-networking

Finally start mysql up with :

# /etc/rc.d/mysqld start

Installing JDBC

JDBC PKGBUILD is currently in AUR repository.

You can also download it from http://www.mysql.com/products/connector-j/ and

( x=mysql-connector-java-*-bin.jar; install -D $x /opt/java/jre/lib/ext/${x##*/} )

Testing

To access mysql's command line tool,

$ mysql

Creating the test database

The following commands create a database and allow a user 'paulr'. You will need to change the user name to whatever yours is.

create database emotherearth;
grant all privileges on emotherearth.* to paulr@localhost identified by "paulr";
flush privileges;

Now press Ctrl+D to exit the command line tool.

Creating the test program

Use an editor to create a file DBDemo.java with the following code in it. You will need to change the username and password appropriately.

import java.sql.*;
import java.util.Properties;
public class DBDemo
{
 // The JDBC Connector Class.
 private static final String dbClassName = "com.mysql.jdbc.Driver";
 // Connection string. emotherearth is the database the program
 // is connecting to. You can include user and password after this
 // by adding (say) ?user=paulr&password=paulr. Not recommended!
 private static final String CONNECTION =
                         "jdbc:mysql://127.0.0.1/emotherearth";
 public static void main(String[] args) throws
                            ClassNotFoundException,SQLException
 {
   System.out.println(dbClassName);
   // Class.forName(xxx) loads the jdbc classes and
   // creates a drivermanager class factory
   Class.forName(dbClassName);
   // Properties for user and password. Here the user and password are both 'paulr'
   Properties p = new Properties();
   p.put("user","paulr");
   p.put("password","paulr");
   // Now try to connect
   Connection c = DriverManager.getConnection(CONNECTION,p);
   System.out.println("It works !");
   c.close();
   }
}

Running the Program

To compile and run the program enter

javac DBDemo.java
java DBDemo

and hopefully, it should print out

This is the database connection
com.mysql.jdbc.Driver
It works !