You can connect and interact with an hosted database like mySQL via php through the AJAX plugin's post and get action. That would require some knowledge of php and mysql, as well as having access to a dedicated web host.
Otherwise, for the use case you have described, the dictionary object may suffice. It can associate a string (key) with any other string (value). You might need to use two dictionary objects that are mirrors of each other to get two way lookup or simply add two entries for each key-value pair, as normally it is one way. This doesn't come anywhere close to the full functionality of an actual database though.
Thank you for your answer, I appreciate it a lot.
Is there any resources to learn how to do that with PHP & MySQL? I'm having a dedicated webhost and would like to try it that way. Unfortunately so far I'm having not much or rather not any knowledge in PHP or MySQL.
Or would you rather recommend me trying it with the Dictionary object?
Best regards and thanks in advance for answers,
Oishii