如果你碰巧改变了这些列

'Doctrine\DBAL\Driver\PDOMySql\Driver' not found

然后安装

作曲家需要学说

加上Dmitri Chebotarev的答案，Laravel 5+。

在要求doctrine/dbal包后:

composer require doctrine/dbal

然后你可以使用可空列进行迁移，如下所示:

public function up()
{
    Schema::table('users', function (Blueprint $table) {
        // change() tells the Schema builder that we are altering a table
        $table->integer('user_id')->unsigned()->nullable()->change();
    });
}

要恢复操作，请执行:

public function down()
{
    /* turn off foreign key checks for a moment */
    DB::statement('SET FOREIGN_KEY_CHECKS = 0');
    /* set null values to 0 first */
    DB::statement('UPDATE `users` SET `user_id` = 0 WHERE `user_id` IS NULL;');
    /* alter table */
    DB::statement('ALTER TABLE `users` MODIFY `user_id` INTEGER UNSIGNED NOT NULL;');
    /* finally turn foreign key checks back on */
    DB::statement('SET FOREIGN_KEY_CHECKS = 1');
}

他是《Laravel 5》的完整迁移:

public function up()
{
    Schema::table('users', function (Blueprint $table) {
        $table->unsignedInteger('user_id')->nullable()->change();
    });
}

public function down()
{
    Schema::table('users', function (Blueprint $table) {
        $table->unsignedInteger('user_id')->nullable(false)->change();
    });
}

关键是，你可以通过传入false作为参数来移除nullable。

安装Composer包:

composer require doctrine/dbal

在成功安装composer包后，我们可以使用迁移命令更改数据类型和更改列名。

语法:

php artisan make:migration alter_table_[table_name]_change_[column_name] --table=[table_name]

例子:

php artisan make:migration alter_table_sessions_change_user_id --table=sessions

<?php

use Illuminate\Database\Migrations\Migration;
use Illuminate\Database\Schema\Blueprint;
use Illuminate\Support\Facades\Schema;

class AlterTableSessionsChangeUserId extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::table('sessions', function (Blueprint $table) {
            $table->integer('user_id')->unsigned()->nullable()->change();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::table('sessions', function (Blueprint $table) {
            $table->dropColumn('user_id');
        });
    }
}

然后运行:php artisan migrate

OR

或刷新表以更改列名。不使用改变方法。

Schema::create('throttle', function(Blueprint $table)
{
    $table->increments('id');
    # old code
    $table->integer('user_id')->unsigned();
    # new code
    $table->integer('user_id')->unsigned()->nullable();
}

注意:以下命令用于清除表中的数据。

php artisan migrate:refresh --path=/database/migrations/2021_09_31_050851_create_throttle_table.php

再加上德米特里·切波塔列夫的回答，

如果你想一次修改多个列，你可以像下面这样做

DB::statement('
     ALTER TABLE `events` 
            MODIFY `event_date` DATE NOT NULL,
            MODIFY `event_start_time` TIME NOT NULL,
            MODIFY `event_end_time` TIME NOT NULL;
');

Laravel 5现在支持更改列;下面是官方文档中的一个例子:

Schema::table('users', function($table)
{
    $table->string('name', 50)->nullable()->change();
});

来源:http://laravel.com/docs/5.0/schema changing-columns

Laravel 4不支持修改列，因此您需要使用另一种技术，例如编写原始SQL命令。例如:

// getting Laravel App Instance
$app = app();

// getting laravel main version
$laravelVer = explode('.',$app::VERSION);

switch ($laravelVer[0]) {

    // Laravel 4
    case('4'):

        DB::statement('ALTER TABLE `pro_categories_langs` MODIFY `name` VARCHAR(100) NULL;');
        break;

    // Laravel 5, or Laravel 6
    default:                

        Schema::table('pro_categories_langs', function(Blueprint $t) {
            $t->string('name', 100)->nullable()->change();
        });               

}