cxinv/app/admin/model/GoodCombind.php

<?php
declare (strict_types = 1);

namespace app\admin\model;

use think\Model;

/**
 * @mixin \think\Model
 */
class GoodCombind extends Model
{
    public function child(){
    	return $this->belongsTo(Good::class,"childCode","spuCode");
    }
}