Laravel makes interacting with databases extremely simple across a variety of database backends using either raw SQL, the fluent query builder, and the Eloquent ORM. Currently, Laravel supports four databases:
The database configuration for your application is located at config/database.php
. In this file you may define all of your database connections, as well as specify which connection should be used by default. Examples for most of the supported database systems are provided in this file.
By default, Laravel's sample environment configuration is ready to use with Laravel Homestead, which is a convenient virtual machine for doing Laravel development on your local machine. You are free to modify this configuration as needed for your local database.
After creating a new SQLite database using a command such as touch database/database.sqlite
, you can easily configure your environment variables to point to this newly created database by using the database's absolute path:
DB_CONNECTION=sqlite DB_DATABASE=/absolute/path/to/database.sqlite
To enable foreign key constraints for SQLite connections, you should set the DB_FOREIGN_KEYS
environment variable to true
:
DB_FOREIGN_KEYS=true
Typically, database connections are configured using multiple configuration values such as host
, database
, username
, password
, etc. Each of these configuration values has its own corresponding environment variable. This means that when configuring your database connection information on a production server, you need to manage several environment variables.
Some managed database providers such as Heroku provide a single database "URL" that contains all of the connection information for the database in a single string. An example database URL may look something like the following:
mysql://root:[email protected]/forge?charset=UTF-8
These URLs typically follow a standard schema convention:
driver://username:password@host:port/database?options
For convenience, Laravel supports these URLs as an alternative to configuring your database with multiple configuration options. If the url
(or corresponding DATABASE_URL
environment variable) configuration option is present, it will be used to extract the database connection and credential information.
Sometimes you may wish to use one database connection for SELECT statements, and another for INSERT, UPDATE, and DELETE statements. Laravel makes this a breeze, and the proper connections will always be used whether you are using raw queries, the query builder, or the Eloquent ORM.
To see how read / write connections should be configured, let's look at this example:
'mysql' => [ 'read' => [ 'host' => [ '192.168.1.1', '196.168.1.2', ], ], 'write' => [ 'host' => [ '196.168.1.3', ], ], 'sticky' => true, 'driver' => 'mysql', 'database' => 'database', 'username' => 'root', 'password' => '', 'charset' => 'utf8mb4', 'collation' => 'utf8mb4_unicode_ci', 'prefix' => '', ],
Note that three keys have been added to the configuration array: read
, write
and sticky
. The read
and write
keys have array values containing a single key: host
. The rest of the database options for the read
and write
connections will be merged from the main mysql
array.
You only need to place items in the read
and write
arrays if you wish to override the values from the main array. So, in this case, 192.168.1.1
will be used as the host for the "read" connection, while 192.168.1.3
will be used for the "write" connection. The database credentials, prefix, character set, and all other options in the main mysql
array will be shared across both connections.
sticky
OptionThe sticky
option is an optional value that can be used to allow the immediate reading of records that have been written to the database during the current request cycle. If the sticky
option is enabled and a "write" operation has been performed against the database during the current request cycle, any further "read" operations will use the "write" connection. This ensures that any data written during the request cycle can be immediately read back from the database during that same request. It is up to you to decide if this is the desired behavior for your application.
When using multiple connections, you may access each connection via the connection
method on the DB
facade. The name
passed to the connection
method should correspond to one of the connections listed in your config/database.php
configuration file:
$users = DB::connection('foo')->select(...);
You may also access the raw, underlying PDO instance using the getPdo
method on a connection instance:
$pdo = DB::connection()->getPdo();
Once you have configured your database connection, you may run queries using the DB
facade. The DB
facade provides methods for each type of query: select
, update
, insert
, delete
, and statement
.
To run a basic query, you may use the select
method on the DB
facade:
<?php namespace App\Http\Controllers; use App\Http\Controllers\Controller; use Illuminate\Support\Facades\DB; class UserController extends Controller { /** * Show a list of all of the application's users. * * @return Response */ public function index() { $users = DB::select('select * from users where active = ?', [1]); return view('user.index', ['users' => $users]); } }
The first argument passed to the select
method is the raw SQL query, while the second argument is any parameter bindings that need to be bound to the query. Typically, these are the values of the where
clause constraints. Parameter binding provides protection against SQL injection.
The select
method will always return an array
of results. Each result within the array will be a PHP stdClass
object, allowing you to access the values of the results:
foreach ($users as $user) { echo $user->name; }
Instead of using ?
to represent your parameter bindings, you may execute a query using named bindings:
$results = DB::select('select * from users where id = :id', ['id' => 1]);
To execute an insert
statement, you may use the insert
method on the DB
facade. Like select
, this method takes the raw SQL query as its first argument and bindings as its second argument:
DB::insert('insert into users (id, name) values (?, ?)', [1, 'Dayle']);
The update
method should be used to update existing records in the database. The number of rows affected by the statement will be returned:
$affected = DB::update('update users set votes = 100 where name = ?', ['John']);
The delete
method should be used to delete records from the database. Like update
, the number of rows affected will be returned:
$deleted = DB::delete('delete from users');
Some database statements do not return any value. For these types of operations, you may use the statement
method on the DB
facade:
DB::statement('drop table users');
If you would like to receive each SQL query executed by your application, you may use the listen
method. This method is useful for logging queries or debugging. You may register your query listener in a service provider:
<?php namespace App\Providers; use Illuminate\Support\Facades\DB; use Illuminate\Support\ServiceProvider; class AppServiceProvider extends ServiceProvider { /** * Register any application services. * * @return void */ public function register() { // } /** * Bootstrap any application services. * * @return void */ public function boot() { DB::listen(function ($query) { // $query->sql // $query->bindings // $query->time }); } }
You may use the transaction
method on the DB
facade to run a set of operations within a database transaction. If an exception is thrown within the transaction Closure
, the transaction will automatically be rolled back. If the Closure
executes successfully, the transaction will automatically be committed. You don't need to worry about manually rolling back or committing while using the transaction
method:
DB::transaction(function () { DB::table('users')->update(['votes' => 1]); DB::table('posts')->delete(); });
The transaction
method accepts an optional second argument which defines the number of times a transaction should be reattempted when a deadlock occurs. Once these attempts have been exhausted, an exception will be thrown:
DB::transaction(function () { DB::table('users')->update(['votes' => 1]); DB::table('posts')->delete(); }, 5);
If you would like to begin a transaction manually and have complete control over rollbacks and commits, you may use the beginTransaction
method on the DB
facade:
DB::beginTransaction();
You can rollback the transaction via the rollBack
method:
DB::rollBack();
Lastly, you can commit a transaction via the commit
method:
DB::commit();
The
DB
facade's transaction methods control the transactions for both the query builder and Eloquent ORM.
© Taylor Otwell
Licensed under the MIT License.
Laravel is a trademark of Taylor Otwell.
https://laravel.com/docs/8.x/database