Think\Db\Query::cache PHP Method

    public function cache($key = true, $expire = null, $tag = null)
    {
        // 增加快捷调用方式 cache(10) 等同于 cache(true, 10)
        if (is_numeric($key) && is_null($expire)) {
            $expire = $key;
            $key = true;
        }
        if (false !== $key) {
            $this->options['cache'] = ['key' => $key, 'expire' => $expire, 'tag' => $tag];
        }
        return $this;
    }