I'm creating a text-based browser game, as a "hobby project", and have come to a small issue I'd like some help with.

One of the actions a player will be able to do is to go on missions. I have a table containing different kinds of missions, and as of right now I pick a few of them at random and display them every time the page loads.

However, I want the ones I pick to be remembered (individualy, for each user). Meaning that those few missions are the only ones which that player can go on that day, and new random missions aren't picked until the next day.

So far I havn't been able to come up with a smart db design for this, and would appreaciate some suggestions.

I what database server model?

Come again?
Perhaps I should have mentioned, I'm likely not as experienced as many people here when it comes to databases. I really don't know what you mean by a "database server model". I'm guessing you're not simply asking what DBM I'm using, but it's MySQL.

depends on what you term as a DBM? To me dBm refers to a signal power ratio.
But in this context I'll assume database manager which would refer to a tool for the management of a database server. Such as phpMyAdmin for MySQL

The database server model would refer to what kind of server it is ie: Oracle, Access, MySQL, PostGre etc.

Most people who are not aufait with database systems seem to believe that MySQL is a language rather than being a server "family"

anyway:

if the table is relatively small (10,000 rows or less)

select fieldlist from table order by rand() limit n;

should work successfully. set the value for limit to suit your use.

Yes, by DBM I meant DataBase Manager :P

According to what I've been tought, a "database" is simply a set of data which in some way refer to each other. It could as well be i.e. a bunch of papers in an old archive. Whereas a DBM is a tool/system which handles (or manages) a database, i.e. MySQL or Oracle.

In those terms, I guess phpMyAdmin would be an... interface(?) or tool which uses a DBM (MySQL in this case).


Anyway, lets return to my problem
I already have a way of selecting the missions randomly (although I did not use rand()). The problem I'm having is to remember those missions, perhaps by storing their IDs in another table or something. I havn't come up with a smart way, well any way actually, to do that.

Let me give an example scenario.
The first time a player opens the mission page, i pick lets say 3 random missions to display. If the player goes to another page, and then returns, he will still see the same 3 missions. Now lets say he does one of the missions, which takes some time, and then comes back to the mission page. Now there are only 2 missions left for him to do. If he does those aswell and then comes back to the mission page, it will just state that there are no more missions right now. The player will not get new missions until the next day, when 3 new missions will be randomly picked.

A database is simply a collection of data items which may or may not have any relationship to each other at all. The only commonality is the structure of the records held within it.
A database could be a simple as a "flat file" (eg: a XML file) or as complex as an "inverted index" data structure.

Oracle and MySQL are database servers. Systems that can hold many different unconnected database structures.

The only "management" available is the built in command language.

Nope, phpMyAdmin IS a database manager.

perhaps by storing their IDs in another table or something.

simplest would be a "missionsCompleted table".

Three columns of userID, MissionID, completed. then it is a simple lookup to determine what each user has done.

Originally Posted by chrishirst

simplest would be a "missionsCompleted table".

Three columns of userID, MissionID, completed. then it is a simple lookup to determine what each user has done.

Ha! Well, that was easy
I can't see why I couldn't think of such a simple idea on my own.
I did just what you wrote, and just added a date field for keeping track of when the missions "expire" and new ones should be picked, and it works like a charm.

Thanks!

And thanks also for clearing up the database and DBM concepts. The course I followed was partly targeted at people who were completely new to databases, so it's quite likely that some things were simplified.

I can't see why I couldn't think of such a simple idea on my own.

As a programmer you will have a certain mindset for the logical progression of program flow and structure, unfortunately that mindset is pretty much at odds with the mindset needed for structuring database schemas, where you need to be able to visualise the whole thing.