user_guide_src/source/database/configuration.rst

######################
Database Configuration
######################

CodeIgniter has a config file that lets you store your database
connection values (username, password, database name, etc.). The config
file is located at application/config/database.php. You can also set
database connection values for specific
:doc:`environments <../libraries/config>` by placing **database.php**
it the respective environment config folder.

The config settings are stored in a multi-dimensional array with this
prototype::

	$db['default']['hostname'] = "localhost"; $db['default']['username'] = "root"; $db['default']['password'] = ""; $db['default']['database'] = "database_name"; $db['default']['dbdriver'] = "mysql"; $db['default']['dbprefix'] = ""; $db['default']['pconnect'] = TRUE; $db['default']['db_debug'] = FALSE; $db['default']['cache_on'] = FALSE; $db['default']['cachedir'] =  ""; $db['default']['char_set'] = "utf8"; $db['default']['dbcollat'] = "utf8_general_ci"; $db['default']['swap_pre'] = ""; $db['default']['autoinit'] = TRUE; $db['default']['stricton'] = FALSE;

The reason we use a multi-dimensional array rather than a more simple
one is to permit you to optionally store multiple sets of connection
values. If, for example, you run multiple environments (development,
production, test, etc.) under a single installation, you can set up a
connection group for each, then switch between groups as needed. For
example, to set up a "test" environment you would do this::

	$db['test']['hostname'] = "localhost"; $db['test']['username'] = "root"; $db['test']['password'] = ""; $db['test']['database'] = "database_name"; $db['test']['dbdriver'] = "mysql"; $db['test']['dbprefix'] = ""; $db['test']['pconnect'] = TRUE; $db['test']['db_debug'] = FALSE; $db['test']['cache_on'] = FALSE; $db['test']['cachedir'] =  ""; $db['test']['char_set'] = "utf8"; $db['test']['dbcollat'] = "utf8_general_ci"; $db['test']['swap_pre'] = ""; $db['test']['autoinit'] = TRUE; $db['test']['stricton'] = FALSE;

Then, to globally tell the system to use that group you would set this
variable located in the config file::

	$active_group = "test";

Note: The name "test" is arbitrary. It can be anything you want. By
default we've used the word "default" for the primary connection, but it
too can be renamed to something more relevant to your project.

Active Record
-------------

The :doc:`Active Record Class <active_record>` is globally enabled or
disabled by setting the $active_record variable in the database
configuration file to TRUE/FALSE (boolean). If you are not using the
active record class, setting it to FALSE will utilize fewer resources
when the database classes are initialized.

::

	$active_record = TRUE;

.. note:: that some CodeIgniter classes such as Sessions require Active
	Records be enabled to access certain functionality.

Explanation of Values:
----------------------

-  **hostname** - The hostname of your database server. Often this is
	"localhost".
-  **username** - The username used to connect to the database.
-  **password** - The password used to connect to the database.
-  **database** - The name of the database you want to connect to.
-  **dbdriver** - The database type. ie: mysql, postgres, odbc, etc.
	Must be specified in lower case.
-  **dbprefix** - An optional table prefix which will added to the table
	name when running :doc:`Active Record <active_record>` queries. This
	permits multiple CodeIgniter installations to share one database.
-  **pconnect** - TRUE/FALSE (boolean) - Whether to use a persistent
	connection.
-  **db_debug** - TRUE/FALSE (boolean) - Whether database errors should
	be displayed.
-  **cache_on** - TRUE/FALSE (boolean) - Whether database query caching
	is enabled, see also :doc:`Database Caching Class <caching>`.
-  **cachedir** - The absolute server path to your database query cache
	directory.
-  **char_set** - The character set used in communicating with the
	database.
-  **dbcollat** - The character collation used in communicating with the
	database.

.. note:: For MySQL and MySQLi databases, this setting is only used
	as a backup if your server is running PHP < 5.2.3 or MySQL < 5.0.7
	(and in table creation queries made with DB Forge). There is an
	incompatibility in PHP with mysql_real_escape_string() which can
	make your site vulnerable to SQL injection if you are using a
	multi-byte character set and are running versions lower than these.
	Sites using Latin-1 or UTF-8 database character set and collation are
	unaffected.

-  **swap_pre** - A default table prefix that should be swapped with
	dbprefix. This is useful for distributed applications where you might
	run manually written queries, and need the prefix to still be
	customizable by the end user.
-  **autoinit** - Whether or not to automatically connect to the
	database when the library loads. If set to false, the connection will
	take place prior to executing the first query.
-  **stricton** - TRUE/FALSE (boolean) - Whether to force "Strict Mode"
	connections, good for ensuring strict SQL while developing an
	application.
-  **port** - The database port number. To use this value you have to
	add a line to the database config
	array.::

	$db['default']['port'] =  5432;


.. note:: Depending on what database platform you are using (MySQL,
	Postgres, etc.) not all values will be needed. For example, when using
	SQLite you will not need to supply a username or password, and the
	database name will be the path to your database file. The information
	above assumes you are using MySQL.