如何使用 mysql 中的 laravel 迁移将数据库列“null”更改为“nullable”？

Question

这是我的车辆表。我想通过使用迁移来更改我的数据库结构

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

class CreateVehiclesTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('vehicles', function (Blueprint $table) {
            $table->increments('id');
            $table->string('image')->nullable();
            $table->string('reg_no')->unique();
            $table->string('fuel_type');
            $table->string('capacity');
            $table->double('rate');
            $table->boolean('req_carrier');
            $table->date('service_date');
            $table->integer('service_freq_km');
            $table->integer('service_freq_months');
            $table->date('insurance_date');
            $table->integer('insurance_freq_months');
            $table->date('eco_date');
            $table->integer('eco_freq_months');
            $table->date('licence_date');
            $table->integer('licence_freq_months');
            $table->integer('current_company');
            $table->string('status')->default("available");
            $table->timestampsTz();

        });
    }

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

我想为这些列赋予可为空的值。1.service_date 2.service_freq_km 3.service_freq_months

如何在 mysql 中将这些列更改为可为空？

Answer 1

您可以阅读有关 的文档Modifying Columns。

如果你想要这些功能，你需要先安装这个包：

composer require doctrine/dbal

然后，您需要创建另一个迁移，例如：

2019_10_24_xxxxxx_change_columns_to_nullable_in_vehicles.php

<?php

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

class ChangeColumnsToNullableInVehicles extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::table('vehicles', function (Blueprint $table) {
            $table->date('service_date')->nullable()->change();
            $table->integer('service_freq_km')->nullable()->change();
            $table->integer('service_freq_months')->nullable()->change();
        });
    }

    /**
     * Reverse the migrations.
     *
     * @return void
     */
    public function down()
    {
        Schema::table('vehicles', function (Blueprint $table) {
            $table->date('service_date')->nullable(false)->change();
            $table->integer('service_freq_km')->nullable(false)->change();
            $table->integer('service_freq_months')->nullable(false)->change();
        });
    }
}