# JDBC and MySQL

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

## Installation

### Installing MySQL

Install a MySQL implementation.

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 service up.

### Installing JDBC

Install a JDBC driver according to your MySQL variant:

- mariadb-jdbc - For the Arch Linux endorsed server.
- mysql-jdbc - For the Oracle variant.

You can also download the latter 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 user. You will need to change the user name to whatever yours is.

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

Category:

- Development