Methods to connect to multiple database in Laravel

To connect to multiple databases in Laravel, you can use the addConnection method in the boot method of your AppServiceProvider.

Here’s an example:

use Illuminate\Support\Facades\DB;
use Illuminate\Support\Facades\Config;

public function boot()
{
    // Add a connection for the second database
    $db2 = Config::get('database.connections.database2');
    Config::set('database.connections.database2', array_merge(
        $db2, ['prefix' => 'database2.']
    ));
    DB::purge('database2');
    DB::reconnect('database2');
}

• The addConnection method shown in the previous example can be added to the boot method of the AppServiceProvider class, which is located in the app/Providers directory. This method will be called every time the application boots, so you can use it to add additional database connections as needed.
• In the addConnection method, we first retrieve the existing configuration for the second database from the config/database.php file using the Config::get method. Then, we merge the existing configuration with a new prefix value using the array_merge function. This prefix will be added to all table names when using the second database connection.
• After updating the configuration, we use the DB::purge and DB::reconnect methods to reset the connection and reconnect to the second database using the updated configuration.

Then, in your config/database.php file, you will need to add your second database connection as an element in the connections array:

'database2' => [
    'driver' => 'mysql',
    'host' => 'localhost',
    'database' => 'database2',
    'username' => 'root',
    'password' => '',
    'charset' => 'utf8',
    'collation' => 'utf8_unicode_ci',
    'prefix' => '',
],

To use the second database in your code, you can use the DB::connection method and pass in the name of the connection as a parameter:

$users = DB::connection('database2')->select('select * from users');

You can also set the default connection for a model by setting the $connection property in the model class:

class User extends Model
{
    protected $connection = 'database2';
}

With this setup, you can use the model’s ::all method to retrieve all users from the second database:

$users = App\User::all();

• To use the second database in your code, you can use the DB::connection method and pass in the name of the connection as a parameter. This will return a new Illuminate\Database\Connection instance configured for the specified connection. You can then use any of the available methods on this instance to query the database, such as select, insert, update, and delete.
• You can also set the default connection for a model by setting the $connection property in the model class. This will cause all queries made through the model to use the specified connection by default. You can still use the DB::connection method to override the default connection for a specific query if needed.

There are a few other ways you can connect to multiple databases in Laravel:

1. You can create a separate database connection for each database you want to connect to, and then specify the connection name when performing queries. For example:

$users = DB::connection('database2')->select('select * from users');
$posts = DB::connection('database3')->select('select * from posts');

2. You can create a custom database connection for each database you want to connect to, and then specify the connection name when performing queries. For example:

use Illuminate\Database\Connectors\ConnectionFactory;
use Illuminate\Database\Connection;

$factory = new ConnectionFactory(app());
$conn = $factory->make([
    'driver' => 'mysql',
    'host' => 'localhost',
    'database' => 'database2',
    'username' => 'root',
    'password' => '',
]);
$conn->setName('database2');
$conn->setPdo($conn->getPdo());

$users = DB::connection('database2')->select('select * from users');

3. You can create a custom database manager that manages multiple database connections and use it to perform queries. For example:

use Illuminate\Database\DatabaseManager;
use Illuminate\Database\Connectors\ConnectionFactory;

$factory = new ConnectionFactory(app());
$manager = new DatabaseManager(app(), $factory);
$manager->extend('database2', function () {
    return [
        'driver' => 'mysql',
        'host' => 'localhost',
        'database' => 'database2',
        'username' => 'root',
        'password' => '',
    ];
});

$users = $manager->connection('database2')->select('select * from users');

Each of these approaches has its own benefits and drawbacks, so you should choose the one that best fits your needs. I hope this helps! Let me know if you have any other questions.