Laravel Migrate

artisan命令行创建migrate

格式：

php artisan make:migration YourFileName

示例：

php artisan make:migration create_books_table

我们找到laravel目录下databasemigrations2017_XX_XX_XXXXXX_create_books_table.php

注意：XX代表时间戳，因时而异

<?php

use IlluminateDatabaseSchemaBlueprint;
use IlluminateDatabaseMigrationsMigration;

class CreateBooksTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        //
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        //
    }
}

这里的CreateBooksTable类继承了Migration，我们看下Migration类

namespace IlluminateDatabaseMigrations;
abstract class Migration
{
    /**
     * The name of the database connection to use.
     *
     * @var string
     */
    protected $connection;
    /**
     * Get the migration connection name.
     *
     * @return string
     */
    public function getConnection()
    {
        return $this->connection;
    }
}

这里我们把up函数改写成

public function up()
{
	Schema::create('chs', function (Blueprint $table) {
		$table->increments('id');			
		$table->string('slug')->unique();//additional
		$table->string('title');//additional
		$table->text('content');//additional
		$table->timestamps();
		$table->timestamp('published_at')->index();//additional
	});
}

同时参考以下文档，文档选自http://laravelbook.com/laravel-migrations-managing-databases/

Laravel Migrate

一切准备就绪，我们开始迁移

php artisan migrate

如果你迁移后发觉并不是你想要的数据表，可以回滚

php artisan migrate:rollback

这里要给大家提个醒，down方法一定要写，可能有些人这个方法会空着，觉得只要数据表创建出来了就没事了，但是一旦涉及rollback又没有down方法，你的migrate操作就是不可逆的！　　

就像这样：

<?php

use IlluminateDatabaseSchemaBlueprint;
use IlluminateDatabaseMigrationsMigration;

class CreateCommentsTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('comments', function (Blueprint $table) {
			$table->increments('id');           
			$table->integer('postid');
			$table->string('title');//additional
			$table->text('content');//additional
			//$table->timestamps();
			$table->timestamp('published_at')->index();//additional
		});
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::drop('comments');
    }
}

Laravel使用了门面模式

namespace IlluminateSupportFacades;
/**
 * @see IlluminateDatabaseSchemaBuilder
 */
class Schema extends Facade
{
    /**
     * Get a schema builder instance for a connection.
     *
     * @param  string  $name
     * @return IlluminateDatabaseSchemaBuilder
     */
    public static function connection($name)
    {
        return static::$app['db']->connection($name)->getSchemaBuilder();
    }
    /**
     * Get a schema builder instance for the default connection.
     *
     * @return IlluminateDatabaseSchemaBuilder
     */
    protected static function getFacadeAccessor()
    {
        return static::$app['db']->connection()->getSchemaBuilder();
    }
}

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