Database migration: laravel

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 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 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:

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

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

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

Drop All Tables & Migrate
The migrate:fresh command will drop all tables from the database and then execute the migrate command:

php artisan migrate:fresh

php artisan migrate:fresh –seed

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');
});

Database Connection & Table Options
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’);
});

Command Description
$table->engine = ‘InnoDB’; Specify the table storage engine (MySQL).
$table->charset = ‘utf8’; Specify a default character set for the table (MySQL).
$table->collation = ‘utf8_unicode_ci’; Specify a default collation for the table (MySQL).
$table->temporary(); Create a temporary table (except SQL Server).

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’); Auto-incrementing UNSIGNED BIGINT (primary key) equivalent column.
$table->bigInteger(‘votes’); BIGINT equivalent column.
$table->binary(‘data’); BLOB equivalent column.
$table->boolean(‘confirmed’); BOOLEAN equivalent column.
$table->char(‘name’, 100); CHAR equivalent column with an optional length.
$table->date(‘created_at’); DATE equivalent column.
$table->dateTime(‘created_at’); DATETIME equivalent column.
$table->dateTimeTz(‘created_at’); DATETIME (with timezone) equivalent column.
$table->decimal(‘amount’, 8, 2); DECIMAL equivalent column with a precision (total digits) and scale (decimal digits).
$table->double(‘amount’, 8, 2); DOUBLE equivalent column with a precision (total digits) and scale (decimal digits).
$table->enum(‘level’, [‘easy’, ‘hard’]); ENUM equivalent column.
$table->float(‘amount’, 8, 2); FLOAT equivalent column with a precision (total digits) and scale (decimal digits).
$table->geometry(‘positions’); GEOMETRY equivalent column.
$table->geometryCollection(‘positions’); GEOMETRYCOLLECTION equivalent column.
$table->increments(‘id’); Auto-incrementing UNSIGNED INTEGER (primary key) equivalent column.
$table->integer(‘votes’); INTEGER equivalent column.
$table->ipAddress(‘visitor’); IP address equivalent column.
$table->json(‘options’); JSON equivalent column.
$table->jsonb(‘options’); JSONB equivalent column.
$table->lineString(‘positions’); LINESTRING equivalent column.
$table->longText(‘description’); LONGTEXT equivalent column.
$table->macAddress(‘device’); MAC address equivalent column.
$table->mediumIncrements(‘id’); Auto-incrementing UNSIGNED MEDIUMINT (primary key) equivalent column.
$table->mediumInteger(‘votes’); MEDIUMINT equivalent column.
$table->mediumText(‘description’); MEDIUMTEXT equivalent column.
$table->morphs(‘taggable’); Adds taggable_id UNSIGNED BIGINT and taggable_type VARCHAR equivalent columns.
$table->multiLineString(‘positions’); MULTILINESTRING equivalent column.
$table->multiPoint(‘positions’); MULTIPOINT equivalent column.
$table->multiPolygon(‘positions’); MULTIPOLYGON equivalent column.
$table->nullableMorphs(‘taggable’); Adds nullable versions of morphs() columns.
$table->nullableTimestamps(); Alias of timestamps() method.
$table->point(‘position’); POINT equivalent column.
$table->polygon(‘positions’); POLYGON equivalent column.
$table->rememberToken(); Adds a nullable remember_token VARCHAR(100) equivalent column.
$table->smallIncrements(‘id’); Auto-incrementing UNSIGNED SMALLINT (primary key) equivalent column.
$table->smallInteger(‘votes’); SMALLINT equivalent column.
$table->softDeletes(); Adds a nullable deleted_at TIMESTAMP equivalent column for soft deletes.
$table->softDeletesTz(); Adds a nullable deleted_at TIMESTAMP (with timezone) equivalent column for soft deletes.
$table->string(‘name’, 100); VARCHAR equivalent column with a optional length.
$table->text(‘description’); TEXT equivalent column.
$table->time(‘sunrise’); TIME equivalent column.
$table->timeTz(‘sunrise’); TIME (with timezone) equivalent column.
$table->timestamp(‘added_on’); TIMESTAMP equivalent column.
$table->timestampTz(‘added_on’); TIMESTAMP (with timezone) equivalent column.
$table->timestamps(); Adds nullable created_at and updated_at TIMESTAMP equivalent columns.
$table->timestampsTz(); Adds nullable created_at and updated_at TIMESTAMP (with timezone) equivalent columns.
$table->tinyIncrements(‘id’); Auto-incrementing UNSIGNED TINYINT (primary key) equivalent column.
$table->tinyInteger(‘votes’); TINYINT equivalent column.
$table->unsignedBigInteger(‘votes’); UNSIGNED BIGINT equivalent column.
$table->unsignedDecimal(‘amount’, 8, 2); UNSIGNED DECIMAL equivalent column with a precision (total digits) and scale (decimal digits).
$table->unsignedInteger(‘votes’); UNSIGNED INTEGER equivalent column.
$table->unsignedMediumInteger(‘votes’); UNSIGNED MEDIUMINT equivalent column.
$table->unsignedSmallInteger(‘votes’); UNSIGNED SMALLINT equivalent column.
$table->unsignedTinyInteger(‘votes’); UNSIGNED TINYINT equivalent column.
$table->uuid(‘id’); UUID equivalent column.
$table->year(‘birth_year’); YEAR equivalent column.

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:

Modifier Description
->after(‘column’) Place the column “after” another column (MySQL)
->autoIncrement() Set INTEGER columns as auto-increment (primary key)
->charset(‘utf8’) Specify a character set for the column (MySQL)
->collation(‘utf8_unicode_ci’) Specify a collation for the column (MySQL/SQL Server)
->comment(‘my comment’) Add a comment to a column (MySQL)
->default($value) Specify a “default” value for the column
->first() Place the column “first” in the table (MySQL)
->nullable($value = true) Allows (by default) NULL values to be inserted into the column
->storedAs($expression) Create a stored generated column (MySQL)
->unsigned() Set INTEGER columns as UNSIGNED (MySQL)
->useCurrent() Set TIMESTAMP columns to use CURRENT_TIMESTAMP as default value
->virtualAs($expression) Create a virtual generated column (MySQL)
->generatedAs($expression) Create an identity column with specified sequence options (PostgreSQL)
->always() Defines the precedence of sequence values over input for an identity column (PostgreSQL)

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();
});