第一件事。
你的table需要一张table primary key . 那会是一个好主意吗 varchar 根据你的例子？mysql的按名称搜索要比比较索引（整数）慢得多。它在理论上的作用（谷歌可以更好地解释）是将文本转换成一个索引并验证它，而索引只是访问它。事实上，我支持拥有一个 id 列作为主键。如果您担心重复，那么可以在列上设置unique site_name .
创建迁移以创建表

php artisan make:migration settings_table

填写迁移代码

<?php

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

class SettingsTable extends Migration
{
    /**
     * Run the migrations.
     *
     * @return void
     */
    public function up()
    {
        Schema::create('settings', function (Blueprint $table) {
            //$table->increments('id'); This will come in hand, trust me
            $table->string('site_name',255)->unique();
            //If you really insist on having site_name as primary key, then use the line below
            // $table->string('site_name',255)->primary();
            $table->string('value',255);
            //$table->timestamps(); Do you need?
        });
    }

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

创造一个有说服力的模型

php artisan make:model Setting

充满你雄辩的模型

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class Setting extends Model
{
    protected $fillable = ['site_name','value'];
    //protected $table = ['settings'] Only if you really need it
    //Usually, if you take Laravel's approach, Models are singular version of the tables, that are in plural, but you can work it as you like
}