HT_DASHBOARD/app/Models/Htpms/MstCustomer.php

<?php

namespace App\Models\Htpms;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Query\Builder;
use Illuminate\Support\Facades\DB;

class MstCustomer extends Model
{
    const COL_NAME_ID = 'id';
    const COL_NAME_CUSTOMER_ID = 'customer_id';
    const COL_NAME_CUSTOMER_NAME = 'customer_name';

    protected $connection = 'htpms';
    protected $table = 'mst_customer';
    protected $fillable = []; // 参照専用

    protected $visible = [
        self::COL_NAME_ID,
        self::COL_NAME_CUSTOMER_ID,
        self::COL_NAME_CUSTOMER_NAME,
    ];

    public static function getBuilder(string $name = 'main'): Builder
    {
        $instance  = new static();
        return DB::connection($instance->getConnectionName())->table(static::getTableName(), $name);
    }

    public static function getTableName(): string
    {
        return (new static)->getTable();
    }
}