December 28, 2018 in Learning, MySql

Database Configuration CodeIgniter

Database Configuration CodeIgniter

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 environments by placing database.php in the respective environment config folder.

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

$db['default'] = array(
        'dsn'   => '',
        'hostname' => 'localhost',
        'username' => 'root',
        'password' => '',
        'database' => 'database_name',
        'dbdriver' => 'mysqli',
        'dbprefix' => '',
        'pconnect' => TRUE,
        'db_debug' => TRUE,
        'cache_on' => FALSE,
        'cachedir' => '',
        'char_set' => 'utf8',
        'dbcollat' => 'utf8_general_ci',
        'swap_pre' => '',
        'encrypt' => FALSE,
        'compress' => FALSE,
        'stricton' => FALSE,
        'failover' => array()
);

Some database drivers (such as PDO, PostgreSQL, Oracle, ODBC) might require a full DSN string to be provided. If that is the case, you should use the ‘dsn’ configuration setting, as if you’re using the driver’s underlying native PHP extension, like this:

// PDO
$db['default']['dsn'] = 'pgsql:host=localhost;port=5432;dbname=database_name';

// Oracle
$db['default']['dsn'] = '//localhost/XE';

Note

If you do not specify a DSN string for a driver that requires it, CodeIgniter will try to build it with the rest of the provided settings.

Note

If you provide a DSN string and it is missing some valid settings (e.g. the database character set), which are present in the rest of the configuration fields, CodeIgniter will append them.

You can also specify failovers for the situation when the main connection cannot connect for some reason. These failovers can be specified by setting the failover for a connection like this:

$db['default']['failover'] = array(
                array(
                        'hostname' => 'localhost1',
                        'username' => '',
                        'password' => '',
                        'database' => '',
                        'dbdriver' => 'mysqli',
                        'dbprefix' => '',
                        'pconnect' => TRUE,
                        'db_debug' => TRUE,
                        'cache_on' => FALSE,
                        'cachedir' => '',
                        'char_set' => 'utf8',
                        'dbcollat' => 'utf8_general_ci',
                        'swap_pre' => '',
                        'encrypt' => FALSE,
                        'compress' => FALSE,
                        'stricton' => FALSE
                ),
                array(
                        'hostname' => 'localhost2',
                        'username' => '',
                        'password' => '',
                        'database' => '',
                        'dbdriver' => 'mysqli',
                        'dbprefix' => '',
                        'pconnect' => TRUE,
                        'db_debug' => TRUE,
                        'cache_on' => FALSE,
                        'cachedir' => '',
                        'char_set' => 'utf8',
                        'dbcollat' => 'utf8_general_ci',
                        'swap_pre' => '',
                        'encrypt' => FALSE,
                        'compress' => FALSE,
                        'stricton' => FALSE
                )
        );

You can specify as many failovers as you like.

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'] = array(
        'dsn'   => '',
        'hostname' => 'localhost',
        'username' => 'root',
        'password' => '',
        'database' => 'database_name',
        'dbdriver' => 'mysqli',
        'dbprefix' => '',
        'pconnect' => TRUE,
        'db_debug' => TRUE,
        'cache_on' => FALSE,
        'cachedir' => '',
        'char_set' => 'utf8',
        'dbcollat' => 'utf8_general_ci',
        'swap_pre' => '',
        'compress' => FALSE,
        'encrypt' => FALSE,
        'stricton' => FALSE,
        'failover' => array()
);

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.

Query Builder

The Query Builder Class is globally enabled or disabled by setting the $query_builder variable in the database configuration file to TRUE/FALSE (boolean). The default setting is TRUE. If you are not using the query builder class, setting it to FALSE will utilize fewer resources when the database classes are initialized.

$query_builder = TRUE;

Note

that some CodeIgniter classes such as Sessions require Query Builder to be enabled to access certain functionality.

Explanation of Values:

Note

Depending on what database platform you are using (MySQL, PostgreSQL, 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.

December 28, 2018 in Learning, MySql

Database Quick Start: Example Code CodeIgniter

Database Quick Start: Example Code CodeIgniter

Database Quick Start: Example Code

The following page contains example code showing how the database class is used. For complete details please read the individual pages describing each function.

Initializing the Database Class

The following code loads and initializes the database class based on your configuration settings:

$this->load->database();

Once loaded the class is ready to be used as described below.

Note: If all your pages require database access you can connect automatically. See the connecting page for details.

Standard Query With Multiple Results (Object Version)

$query = $this->db->query('SELECT name, title, email FROM my_table');

foreach ($query->result() as $row)
{
        echo $row->title;
        echo $row->name;
        echo $row->email;
}

echo 'Total Results: ' . $query->num_rows();

The above result() function returns an array of objects. Example: $row->title

Standard Query With Multiple Results (Array Version)

$query = $this->db->query('SELECT name, title, email FROM my_table');

foreach ($query->result_array() as $row)
{
        echo $row['title'];
        echo $row['name'];
        echo $row['email'];
}
The above result_array() function returns an array of standard array indexes. Example: $row[‘title’]

Standard Query With Single Result

$query = $this->db->query('SELECT name FROM my_table LIMIT 1');
$row = $query->row();
echo $row->name;

The above row() function returns an object. Example: $row->name

Standard Query With Single Result (Array version)

$query = $this->db->query('SELECT name FROM my_table LIMIT 1');
$row = $query->row_array();
echo $row['name'];

The above row_array() function returns an array. Example: $row[‘name’]

Standard Insert

$sql = "INSERT INTO mytable (title, name) VALUES (".$this->db->escape($title).", ".$this->db->escape($name).")";
$this->db->query($sql);
echo $this->db->affected_rows();

Query Builder Query

The Query Builder Pattern gives you a simplified means of retrieving data:

$query = $this->db->get('table_name');

foreach ($query->result() as $row) { echo $row->title; }

The above get() function retrieves all the results from the supplied table. The Query Builder class contains a full compliment of functions for working with data.

Query Builder Insert

$data = array(
        'title' => $title,
        'name' => $name,
        'date' => $date
);

$this->db->insert('mytable', $data);  // Produces: INSERT INTO mytable (title, name, date) VALUES ('{$title}', '{$name}', '{$date}')