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 core 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.
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'] = "mysql";
$config['dbprefix'] = "";
$config['pconnect'] = FALSE;
$config['db_debug'] = TRUE;
$config['active_r'] = TRUE;
$this->load->database($config);
For information on each of these values please see the configuration page.
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');
Note that if you use a DSN you will not be able to specify some of the default values like you can if you use a connection array.
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.
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...