book_admin/application/common/model/CpVipList.php

<?php

namespace app\common\model;

use think\Model;

class CpVipList extends Model
{
    // 表名
    protected $table = 'cp_vip_list';

    // 自动写入时间戳字段
    protected $autoWriteTimestamp = 'int';

    // 定义时间戳字段名
    protected $createTime = 'createtime';
    protected $updateTime = 'updatetime';

    // 追加属性
    protected $append = [

    ];


    /**
     * 返回所有book_id
     * @return string
     */
    public function getBookIds(){
        $data = $this->field('book_id')->select();
        $ids = implode(',',array_column($data, 'book_id'));
        return $ids;
    }

}