$ rails example // Rails 2.x
$ rails new example // Rails 3.x

is that by default a generated project is configured to use a SQLite database. And so the configuration file for the databases looks as shown below (I omit the configurations for the “test” and “production” environments, as they are almost identical):

# example/config/database.yml
development:
  adapter: sqlite3
  database: db/development.sqlite3
  pool: 5
  timeout: 5000

This leads, of course, to an error as soon as you try to access the database while there is no such driver installed ;-)

To avoid this small problem, you have to specify the database type when using the “rails” command:

$ rails -d mysql example // Rails 2.x
$ rails new example -d mysql // Rails 3.x

This command then generates the following database.yml:

# example/config/database.yml
development:
  adapter: mysql  # Rails 3.x uses the mysql2 adapter
  encoding: utf8
  database: example_development
  pool: 5
  username: root
  password:
  socket: /var/run/mysqld/mysqld.sock

Happy Rails baking!

Update 2009-03-23: An alternative approach in Rails 2.x is to define the variable RAILS_DEFAULT_DATABASE with:

$ export RAILS_DEFAULT_DATABASE=mysql

Update 2011-02-20: Adapted for Rails3

Ok, let’s do some examples to learn more about it. We will use the following countries table:

[1] => USA
[2] => Germany
[3] => Russia
[4] => Austria
[5] => China
[6] => Switzerland

Now, we don’t want to sort them by the id, but by some “strange” order: Austria, USA, China, Russia, Switzerland, Germany. For this purpose we can use “order by field”: the first parameter is the column name and all following parameters are values of the respective column. In CakePHP it is done in the following way:

$this->Country->find('list', array('order' => array('FIELD(Country.id, 4, 1, 5, 3, 6, 2)')));

And we get the expected result:

[4] => Austria
[1] => USA
[5] => China
[3] => Russia
[6] => Switzerland
[2] => Germany

Probably more common is the scenario that you want to have certain values at the top of a list, and the other values of the list should be ordered alphabetically. If we want the German-speaking countries at the top of the list we would do:

$this->Country->find('list', array('order' => array('FIELD(Country.id, 2, 4, 6)', 'Country.name')));

or 

$this->Country->find('list', array('order' => array('FIELD(Country.name, "Germany", "Austria", "Switzerland")', 'Country.name')));

Unfortunately, this doesn’t return the expected result, the records which should be at the top are at the bottom:

[5] => China
[3] => Russia
[1] => USA
[2] => Germany
[4] => Austria
[6] => Switzerland

We can solve this “problem” by using the “DESC” keyword and changing the order of the provided values:

$this->Country->find('list', array('order' => array('FIELD(Country.id, 6, 4, 2) DESC', 'Country.name')));

or

$this->Country->find('list', array('order' => array('FIELD(Country.name, "Switzerland", "Austria", "Germany") DESC', 'Country.name')))

With those changes we get the expected result:

[2] => Germany
[4] => Austria
[6] => Switzerland
[5] => China
[3] => Russia
[1] => USA

Thanks to Tarique for mentioning “order by field” and to Abhimanyu Grover for asking the original question.

$this->Post->findAll(
    'WHERE Post.created >= DATE_SUB(CURDATE(), INTERVAL 30 DAY)');

Well, today I saw a solution, presented by nate in a post in the google group:

// app/app_model.php
class AppModel extends Model
{
    function __construct()
    {
        parent::__construct();
        $this->execute("Set NAMES 'UTF8'");
    }
}

And that is the way I had to learn it: In my app the user can upload files, and these files are stored in the database. Everything worked fine with small files. But for some reason it didn’t work with larger files. If I tried to download the uploaded files, the download was discontinued after a short time period. “Probably a timeout problem”, I thought. And so I searched in this area for the cause of the problem. Without result. By accident I landed on the page “Data Type Storage Requirements”, and I got the “Aha” effect. I used the wrong data type: “BLOB” supports only data up to 64kb…

Another learning from this episode is that the cause of a problem is sometimes not there where you are looking for…

Since it worked when I entered the euro sign in my application, the problem had to be in my sql scripts or in my ant script I use to execute the sql scripts. The sql scripts were ok, as they worked when executed via MySQL Query Browser. So the problem had to be in my ant script. But what was the cause of the problem? After searching for a long time I found the problem: I have to specify the encoding in the URL used by JDBC. Instead of

jdbc:mysql://localhost/mydb

I have to use

jdbc:mysql://localhost/mydb?characterEncoding=UTF-8

Oh, I really love this entire encoding stuff ;-)

[mysqld]
init-connect = 'SET NAMES utf8'

If you do not have access to this file, you can alternatively execute the statement “SET NAMES utf8″ before you do any sql queries (I have not tested this approach).

• there is a new constant called CAKE_SESSION_STRING in core.php
• app/controllers/components/db_acl.sql has been removed (it is the one I used for my unsuccessful dbAcl experiments *g*)
• AjaxHelper::linkToRemote() is now deprecated, it is replaced by AjaxHelper::link()
• dbAcl has been updated, so it is time for a new dbAcl experiment ;-)
• there are some new convenience methods: up() for strtoupper(), low() for strtolower(), and r() for str_replace()
• transaction support for MySQL
• a lot of changes for the PostgreSQL driver

So, it is time to test if my application still works with this update :)