Don't wait until everything is just right. It will never be perfect. There will always be challenges, obstacles and less than perfect conditions. So what. Get started now. With each step you take, you will grow stronger and stronger, more and more skilled, more and more self-confident and more and more successful.

The only thing that can stop you is you.

关系型数据库管理方法不仅仅是一种技术；它是一种关于数据的思考方式。

挑战让生活变得有趣；克服挑战让生活变得有意义。