+ +
+

Connecting to your Database

+

There are two ways to connect to a database:

+
+

Automatically Connecting

+

The “auto connect” feature will load and instantiate the database class +with every page load. To enable “auto connecting”, add the word database +to the library array, as indicated in the following file:

+

application/config/autoload.php

+
+
+

Manually Connecting

+

If only some of your pages require database connectivity you can +manually connect to your database by adding this line of code in any +function where it is needed, or in your class constructor to make the +database available globally in that class.

+
$this->load->database();
+
+
+

If the above function does not contain any information in the first +parameter it will connect to the group specified in your database config +file. For most people, this is the preferred method of use.

+
+

Available Parameters

+
    +
  1. The database connection values, passed either as an array or a DSN +string.
    2. +
  2. TRUE/FALSE (boolean). Whether to return the connection ID (see +Connecting to Multiple Databases below).
    3. +
  3. TRUE/FALSE (boolean). Whether to enable the Query Builder class. Set +to TRUE by default.
    4. +
+
+
+

Manually Connecting to a Database

+

The first parameter of this function can optionally be used to +specify a particular database group from your config file, or you can +even submit connection values for a database that is not specified in +your config file. Examples:

+

To choose a specific group from your config file you can do this:

+
$this->load->database('group_name');
+
+
+

Where group_name is the name of the connection group from your config +file.

+

To connect manually to a desired database you can pass an array of +values:

+
$config['hostname'] = 'localhost';
+$config['username'] = 'myusername';
+$config['password'] = 'mypassword';
+$config['database'] = 'mydatabase';
+$config['dbdriver'] = 'mysqli';
+$config['dbprefix'] = '';
+$config['pconnect'] = FALSE;
+$config['db_debug'] = TRUE;
+$config['cache_on'] = FALSE;
+$config['cachedir'] = '';
+$config['char_set'] = 'utf8';
+$config['dbcollat'] = 'utf8_general_ci';
+$this->load->database($config);
+
+
+

For information on each of these values please see the configuration +page.

+
+

Note

+

For the PDO driver, you should use the $config[‘dsn’] setting +instead of ‘hostname’ and ‘database’:

+
+

+
$config[‘dsn’] = ‘mysql:host=localhost;dbname=mydatabase’;
+
+
+

Or you can submit your database values as a Data Source Name. DSNs must +have this prototype:

+
$dsn = 'dbdriver://username:password@hostname/database';
+$this->load->database($dsn);
+
+
+

To override default config values when connecting with a DSN string, add +the config variables as a query string.

+
$dsn = 'dbdriver://username:password@hostname/database?char_set=utf8&dbcollat=utf8_general_ci&cache_on=true&cachedir=/path/to/cache';
+$this->load->database($dsn);
+
+
+
+
+
+

Connecting to Multiple Databases

+

If you need to connect to more than one database simultaneously you can +do so as follows:

+
$DB1 = $this->load->database('group_one', TRUE);
+$DB2 = $this->load->database('group_two', TRUE);
+
+
+

Note: Change the words “group_one” and “group_two” to the specific +group names you are connecting to (or you can pass the connection values +as indicated above).

+

By setting the second parameter to TRUE (boolean) the function will +return the database object.

+
+

Note

+

When you connect this way, you will use your object name to issue +commands rather than the syntax used throughout this guide. In other +words, rather than issuing commands with:

+
+

+
$this->db->query();
+
$this->db->result();
+
etc…
+

+
You will instead use:
+

+
$DB1->query();
+
$DB1->result();
+
etc…
+
+
+
+

Note

+

You don’t need to create separate database configurations if you +only need to use a different database on the same connection. You +can switch to a different database when you need to, like this:

+
+
$this->db->db_select($database2_name);
+
+
+
+
+

Reconnecting / Keeping the Connection Alive

+

If the database server’s idle timeout is exceeded while you’re doing +some heavy PHP lifting (processing an image, for instance), you should +consider pinging the server by using the reconnect() method before +sending further queries, which can gracefully keep the connection alive +or re-establish it.

+
$this->db->reconnect();
+
+
+
+
+

Manually closing the Connection

+

While CodeIgniter intelligently takes care of closing your database +connections, you can explicitly close the connection.

+
$this->db->close();
+
+
+
+
+ + +