[RESOLVED] Public database - Access problem?

[JoakimG]

Hi

Im developing a "simple" database, its not an SQL, since im not familiar with that. I've just made a sort of database, consisting of a list of objects. So its just a simple list really (but where the list items hold many different types of data, this is the easiest way to coordinate the data I need to hold in the database, so im gonna avoid SQL as long as I can).

But im getting concerns of how the application that manages the "database" will work when more than one user is active.

Do I need to make a User-application and a server application and use threads or will this solve it self do you think?

The application was first planned to be on a "public" server, where just anyone (with the right permissions) could explore to and run the application. I dont think there will be any problems searching the database with several users online (and this will really be the most common action taken), but what if there will be two users online at the same time who are trying to add data to the database? This is my biggest concern.

But there is another fact to have in mind, is that the total number of users in my comapny wont be more than 10. And they will mostly not be online at the same time. So this problem really will almost never occur.
But still.....

[randem]

Avoiding SQL is not a smart thing to do. It makes the whole process a lot simpler and it's not that hard. SQL is basically self documenting and when maintenance issues come into play you will be glad it's there.

For multi-user database applications you might want to look at this project for ideas on how it should work http://www.***********/freeware.html#...ncy%20Checking

[JoakimG]

The thing is I don't want the "table" database. In my case I find it alot better with a normal list of the object since the data I'm storing is complicated and there are alot of different types of data to be stored for each object.

I've had some people giving me advice about using linked tables and so on. But it will get really messy in my case because I have to have 4 different databases, because I want to store 4 different types of materials. Then I would need about 4*30 different tables to store data in, since the materials each have around 30 "values". Where some values in themselves are two dimensional arrays (a normal example of this kind of data is temperature dependent elasticity modulus, or youngs modulus).

So for what I can see, I need 4*30, where some data in tables are linked to other tables, so that would mean 4*30+4*5 tables in total (maybe).
Am I completly wrong in assuming this? Remember I have never used SQL before and im not a "real" programmer.

I however know that SQL have methods of dealing with the problem at hand (multiple users online at the same time) built in. So that this problem would be solved.

[randem]

No it would not mean anything close to that. That is why one would normalize the data. You would only need one database and no where near the number of tables you think you do.

[JoakimG]

Not sure what you mean by normalize the data. The data for the different material types (plastic, metal, paper) are so different that there are only a couple of variables that have the same format, such as ID. For the simple density some materials have an array, and some have a normal Double, and so on.

[randem]

You can't impose your knowledge of a database on the database itself. The database can handle it. They have been for over 30 years. What you are doing is nothing new. Just new to you...

[JoakimG]

So a really dumb question then, can you store arrays in a database?
Kepp in mind that the array may be anything from 1-1000 elelents long (but probably around 80 elements, just want to show that it has to be able to store arrays that are dynamically assigned by the user)
What kind of data can be stored in a SQL database table? In each "element" that is.

[randem]

Sure you can, That is what a BLOB field can do. Blob fields can store RAW (Binary) data so it really doesn't matter what is in it. Since you are not searching in it you just set up keys so that you can retrieve the BLOB data and restore it to the form you need to process in your app.

[JoakimG]

You can?!?
Thats fantastic news, finally someone tells me what I want to hear!
I'm gonna look into this more today, because that sounds really interesting.
Thanks for the help!