Introduction
Migrations are like version control for your database, allowing your team to easily modify and share the application's database schema. Migrations are typically paired with Laravel's schema builder to easily build your application's database schema. If you have ever had to tell a teammate to manually add a column to their local database schema, you've faced the problem that database migrations solve.
The Laravel Schema facade provides database
agnostic support for creating and manipulating tables
across all of Laravel's supported database systems.
Generating Migrations
To create a migration, use the
make:migration Artisan command:
php artisan make:migration create_users_table
The new migration will be placed in your
database/migrations directory. Each
migration file name contains a timestamp which allows
Laravel to determine the order of the migrations.
The --table and --create
options may also be used to indicate the name of the
table and whether the migration will be creating a new
table. These options simply pre-fill the generated
migration stub file with the specified table:
php artisan make:migration create_users_table --create=users
php artisan make:migration add_votes_to_users_table --table=users
If you would like to specify a custom output path for the
generated migration, you may use the --path
option when executing the make:migration
command. The given path should be relative to your
application's base path.
Migration Structure
A migration class contains two methods: up
and down. The up method is
used to add new tables, columns, or indexes to your
database, while the down method should
simply reverse the operations performed by the
up method.
Within both of these methods you may use the Laravel
schema builder to expressively create and modify tables.
To learn about all of the methods available on the
Schema builder, check out its
documentation. For example, this migration
example creates a flights table:
<?php
use Illuminate\Support\Facades\Schema;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Database\Migrations\Migration;
class CreateFlightsTable extends Migration
{
/**
* Run the migrations.
*
* @return void
*/
public function up()
{
Schema::create('flights', function (Blueprint $table) {
$table->increments('id');
$table->string('name');
$table->string('airline');
$table->timestamps();
});
}
/**
* Reverse the migrations.
*
* @return void
*/
public function down()
{
Schema::drop('flights');
}
}
Running Migrations
To run all of your outstanding migrations, execute the
migrate Artisan command:
php artisan migrate
Note: If you are using the Homestead virtual machine, you should run this command from within your virtual machine.
Forcing Migrations To Run In Production
Some migration operations are destructive, which means
they may cause you to lose data. In order to protect you
from running these commands against your production
database, you will be prompted for confirmation before
the commands are executed. To force the commands to run
without a prompt, use the --force flag:
php artisan migrate --force
Rolling Back Migrations
To rollback the latest migration operation, you may use
the rollback command. This command rolls
back the last "batch" of migrations, which may
include multiple migration files:
php artisan migrate:rollback
You may rollback a limited number of migrations by
providing the step option to the
rollback command. For example, the
following command will rollback the last five
migrations:
php artisan migrate:rollback --step=5
The migrate:reset command will roll back all
of your application's migrations:
php artisan migrate:reset
Rollback & Migrate In Single Command
The migrate:refresh command will roll back
all of your migrations and then execute the
migrate command. This command effectively
re-creates your entire database:
php artisan migrate:refresh
// Refresh the database and run all database seeds...
php artisan migrate:refresh --seed
You may rollback & re-migrate a limited number of
migrations by providing the step option to
the refresh command. For example, the
following command will rollback & re-migrate the
last five migrations:
php artisan migrate:refresh --step=5
Tables
Creating Tables
To create a new database table, use the
create method on the Schema
facade. The create method accepts two
arguments. The first is the name of the table, while the
second is a Closure which receives a
Blueprint object that may be used to define
the new table:
Schema::create('users', function (Blueprint $table) {
$table->increments('id');
});
Of course, when creating the table, you may use any of the schema builder's column methods to define the table's columns.
Checking For Table / Column Existence
You may easily check for the existence of a table or
column using the hasTable and
hasColumn methods:
if (Schema::hasTable('users')) {
//
}
if (Schema::hasColumn('users', 'email')) {
//
}
Connection & Storage Engine
If you want to perform a schema operation on a database
connection that is not your default connection, use the
connection method:
Schema::connection('foo')->create('users', function (Blueprint $table) {
$table->increments('id');
});
You may use the engine property on the
schema builder to define the table's storage engine:
Schema::create('users', function (Blueprint $table) {
$table->engine = 'InnoDB';
$table->increments('id');
});
Renaming / Dropping Tables
To rename an existing database table, use the
rename method:
Schema::rename($from, $to);
To drop an existing table, you may use the
drop or dropIfExists
methods:
Schema::drop('users');
Schema::dropIfExists('users');
Renaming Tables With Foreign Keys
Before renaming a table, you should verify that any foreign key constraints on the table have an explicit name in your migration files instead of letting Laravel assign a convention based name. Otherwise, the foreign key constraint name will refer to the old table name.
Columns
Creating Columns
The table method on the Schema
facade may be used to update existing tables. Like the
create method, the table
method accepts two arguments: the name of the table and
a Closure that receives a
Blueprint instance you may use to add
columns to the table:
Schema::table('users', function (Blueprint $table) {
$table->string('email');
});
Available Column Types
Of course, the schema builder contains a variety of column types that you may specify when building your tables:
| Command | Description |
|---|---|
$table->bigIncrements('id'); |
Incrementing ID (primary key) using a "UNSIGNED BIG INTEGER" equivalent. |
$table->bigInteger('votes'); |
BIGINT equivalent for the database. |
$table->binary('data'); |
BLOB equivalent for the database. |
$table->boolean('confirmed'); |
BOOLEAN equivalent for the database. |
$table->char('name',
4); |
CHAR equivalent with a length. |
$table->date('created_at'); |
DATE equivalent for the database. |
$table->dateTime('created_at'); |
DATETIME equivalent for the database. |
$table->dateTimeTz('created_at'); |
DATETIME (with timezone) equivalent for the database. |
$table->decimal('amount', 5,
2); |
DECIMAL equivalent with a precision and scale. |
$table->double('column', 15,
8); |
DOUBLE equivalent with precision, 15 digits in total and 8 after the decimal point. |
$table->enum('choices', ['foo',
'bar']); |
ENUM equivalent for the database. |
$table->float('amount', 8,
2); |
FLOAT equivalent for the database, 8 digits in total and 2 after the decimal point. |
$table->increments('id'); |
Incrementing ID (primary key) using a "UNSIGNED INTEGER" equivalent. |
$table->integer('votes'); |
INTEGER equivalent for the database. |
$table->ipAddress('visitor'); |
IP address equivalent for the database. |
$table->json('options'); |
JSON equivalent for the database. |
$table->jsonb('options'); |
JSONB equivalent for the database. |
$table->longText('description'); |
LONGTEXT equivalent for the database. |
$table->macAddress('device'); |
MAC address equivalent for the database. |
$table->mediumIncrements('id'); |
Incrementing ID (primary key) using a "UNSIGNED MEDIUM INTEGER" equivalent. |
$table->mediumInteger('numbers'); |
MEDIUMINT equivalent for the database. |
$table->mediumText('description'); |
MEDIUMTEXT equivalent for the database. |
$table->morphs('taggable'); |
Adds unsigned INTEGER
taggable_id and STRING
taggable_type. |
$table->nullableMorphs('taggable'); |
Nullable versions of the
morphs() columns. |
$table->nullableTimestamps(); |
Nullable versions of the
timestamps() columns. |
$table->rememberToken(); |
Adds remember_token as
VARCHAR(100) NULL. |
$table->smallIncrements('id'); |
Incrementing ID (primary key) using a "UNSIGNED SMALL INTEGER" equivalent. |
$table->smallInteger('votes'); |
SMALLINT equivalent for the database. |
$table->softDeletes(); |
Adds nullable deleted_at column
for soft deletes. |
$table->string('email'); |
VARCHAR equivalent column. |
$table->string('name',
100); |
VARCHAR equivalent with a length. |
$table->text('description'); |
TEXT equivalent for the database. |
$table->time('sunrise'); |
TIME equivalent for the database. |
$table->timeTz('sunrise'); |
TIME (with timezone) equivalent for the database. |
$table->tinyInteger('numbers'); |
TINYINT equivalent for the database. |
$table->timestamp('added_on'); |
TIMESTAMP equivalent for the database. |
$table->timestampTz('added_on'); |
TIMESTAMP (with timezone) equivalent for the database. |
$table->timestamps(); |
Adds nullable created_at and
updated_at columns. |
$table->timestampsTz(); |
Adds nullable created_at and
updated_at (with timezone)
columns. |
$table->unsignedBigInteger('votes'); |
Unsigned BIGINT equivalent for the database. |
$table->unsignedInteger('votes'); |
Unsigned INT equivalent for the database. |
$table->unsignedMediumInteger('votes'); |
Unsigned MEDIUMINT equivalent for the database. |
$table->unsignedSmallInteger('votes'); |
Unsigned SMALLINT equivalent for the database. |
$table->unsignedTinyInteger('votes'); |
Unsigned TINYINT equivalent for the database. |
$table->uuid('id'); |
UUID equivalent for the database. |
Column Modifiers
In addition to the column types listed above, there are
several column "modifiers" you may use while
adding a column to a database table. For example, to
make the column "nullable", you may use the
nullable method:
Schema::table('users', function (Blueprint $table) {
$table->string('email')->nullable();
});
Below is a list of all the available column modifiers. This list does not include the index modifiers:
| Modifier | Description |
|---|---|
->after('column') |
Place the column "after" another column (MySQL Only) |
->comment('my comment') |
Add a comment to a column |
->default($value) |
Specify a "default" value for the column |
->first() |
Place the column "first" in the table (MySQL Only) |
->nullable() |
Allow NULL values to be inserted into the column |
->storedAs($expression) |
Create a stored generated column (MySQL Only) |
->unsigned() |
Set integer columns to
UNSIGNED |
->virtualAs($expression) |
Create a virtual generated column (MySQL Only) |
Modifying Columns
Prerequisites
Before modifying a column, be sure to add the
doctrine/dbal dependency to your
composer.json file. The Doctrine DBAL
library is used to determine the current state of the
column and create the SQL queries needed to make the
specified adjustments to the column:
composer require doctrine/dbal
Updating Column Attributes
The change method allows you to modify some
existing column types to a new type or modify the
column's attributes. For example, you may wish to
increase the size of a string column. To see the
change method in action, let's increase the
size of the name column from 25 to 50:
Schema::table('users', function (Blueprint $table) {
$table->string('name', 50)->change();
});
We could also modify a column to be nullable:
Schema::table('users', function (Blueprint $table) {
$table->string('name', 50)->nullable()->change();
});
Note: The following column types can not be "changed": char, double, enum, mediumInteger, timestamp, tinyInteger, ipAddress, json, jsonb, macAddress, mediumIncrements, morphs, nullableMorphs, nullableTimestamps, softDeletes, timeTz, timestampTz, timestamps, timestampsTz, unsignedMediumInteger, unsignedTinyInteger, uuid.
Renaming Columns
To rename a column, you may use the
renameColumn method on the Schema builder.
Before renaming a column, be sure to add the
doctrine/dbal dependency to your
composer.json file:
Schema::table('users', function (Blueprint $table) {
$table->renameColumn('from', 'to');
});
Note: Renaming any column in a table that also has a column of type
enumis not currently supported.
Dropping Columns
To drop a column, use the dropColumn method
on the Schema builder. Before dropping columns from a
SQLite database, you will need to add the
doctrine/dbal dependency to your
composer.json file and run the
composer update command in your terminal to
install the library:
Schema::table('users', function (Blueprint $table) {
$table->dropColumn('votes');
});
You may drop multiple columns from a table by passing an
array of column names to the dropColumn
method:
Schema::table('users', function (Blueprint $table) {
$table->dropColumn(['votes', 'avatar', 'location']);
});
Note: Dropping or modifying multiple columns within a single migration while using a SQLite database is not supported.
Indexes
Creating Indexes
The schema builder supports several types of indexes.
First, let's look at an example that specifies a
column's values should be unique. To create the index,
we can simply chain the unique method onto
the column definition:
$table->string('email')->unique();
Alternatively, you may create the index after defining the column. For example:
$table->unique('email');
You may even pass an array of columns to an index method to create a compound index:
$table->index(['account_id', 'created_at']);
Laravel will automatically generate a reasonable index name, but you may pass a second argument to the method to specify the name yourself:
$table->index('email', 'my_index_name');
Available Index Types
| Command | Description |
|---|---|
$table->primary('id'); |
Add a primary key. |
$table->primary(['first',
'last']); |
Add composite keys. |
$table->unique('email'); |
Add a unique index. |
$table->unique('state',
'my_index_name'); |
Add a custom index name. |
$table->unique(['first',
'last']); |
Add a composite unique index. |
$table->index('state'); |
Add a basic index. |
Dropping Indexes
To drop an index, you must specify the index's name. By default, Laravel automatically assigns a reasonable name to the indexes. Simply concatenate the table name, the name of the indexed column, and the index type. Here are some examples:
| Command | Description |
|---|---|
$table->dropPrimary('users_id_primary'); |
Drop a primary key from the "users" table. |
$table->dropUnique('users_email_unique'); |
Drop a unique index from the "users" table. |
$table->dropIndex('geo_state_index'); |
Drop a basic index from the "geo" table. |
If you pass an array of columns into a method that drops indexes, the conventional index name will be generated based on the table name, columns and key type:
Schema::table('geo', function (Blueprint $table) {
$table->dropIndex(['state']); // Drops index 'geo_state_index'
});
Foreign Key Constraints
Laravel also provides support for creating foreign key
constraints, which are used to force referential
integrity at the database level. For example, let's
define a user_id column on the
posts table that references the
id column on a users
table:
Schema::table('posts', function (Blueprint $table) {
$table->integer('user_id')->unsigned();
$table->foreign('user_id')->references('id')->on('users');
});
You may also specify the desired action for the "on delete" and "on update" properties of the constraint:
$table->foreign('user_id')
->references('id')->on('users')
->onDelete('cascade');
To drop a foreign key, you may use the
dropForeign method. Foreign key constraints
use the same naming convention as indexes. So, we will
concatenate the table name and the columns in the
constraint then suffix the name with
"_foreign":
$table->dropForeign('posts_user_id_foreign');
Or, you may pass an array value which will automatically use the conventional constraint name when dropping:
$table->dropForeign(['user_id']);
You may enable or disable foreign key constraints within your migrations by using the following methods:
Schema::enableForeignKeyConstraints();
Schema::disableForeignKeyConstraints();