我正在使用 Nodejs 并使用expressjs框架，现在我正在尝试获取 “最后插入的 id”，但我在控制台中收到“未定义”，如何获取最后插入的 id？这是我当前的代码

static async addServiceDetail(salonId,serviceId,genderTypeId,price,serviceName)
    {
        const sql = `SELECT id from hc_servicesdetail WHERE shopId='${shopId}' AND  serviceId='${serviceId}' AND genderTypeId='genderTypeId'`;
        const [rows, fields] = await pool.execute(sql);
        if(rows<1)
            {
                const sql2 = `INSERT INTO hc_servicesdetail (shopId, serviceId, genderTypeId,price,serviceName) VALUES ("${shopId}", "${serviceId}", "${genderTypeId}", "${price}","${serviceName}")`;
                const datass = await pool.execute(sql2);
                console.log('last inserted id is ' +datass.insertId);
            }
        else
            {
                console.log('already exist');
            }   
    }
}

module.exports = User;