在mysql中存储密码...使用哈希吧？但是如何向用户发送忘记密码？

I've been looking into storing user passwords in mysql and the ubiquitous reply is to store it using an encryption algorithm like MD5 or SHA1. But what if user x forgets her password and wants it to be sent to her? What then? I can't send her the md5 hash! How is this issue dealt with in the real world. Are there two databases? One to compare hashes and another for forgotten passwords? But what's the difference, both would be read-only by the sql user connecting to it at that time. So how do you do it? Thanks!!I've been looking into storing user passwords i