Database Programming

[Valleriani]

Using VB

Okay, I have a Access database going on that stores all the data. Would it be better to do either:

1) Get the info from the database, store them in variables(array s), call them when needed, then when needed have them save all using some sort of /save command or such.

OR

2) Call the info when needed right from the DB, and directly save it when something changes..



This is using the Microsoft DAO 3.6 Library...
What I'm asking is. Can I call straight from the DB all the time? Or will it cause lag... Basicly: Should it be called and stored into variables then saved back into the DB using those variables, so it would not save if a crash occured? Or can I call it right to the client, and have it save soon as something updates?

This is for server to client stuff.

[Valleriani]

Basicly the first one would be /save only when I type it, or per few minutes.

And the second one would be real-time. Saving when something changes.

Got to remember there may be 100-150 people using it always.

[CaptainD]

If their pulling data and not staying connected to the database, then they can access it at anytime. As a rule it is not recommended (By microsoft) to have more then 5 or 10 people on a *.mdb but there are people that say they have 150 users on one. You just have to be careful how you're set up. You would not want to try and have all 100 + connected at the same time.

As far as when to update, in my opinion, it should be updated as soon as there is a change. That way person X gets the data and after the change is made and saved, person Y gets the updated information. If person X gets the data and the change is saved on their computer, then person Y gets the data, it's "old" data. Then you run into the person X and Y make changes to the old data and each over write each other. (Y changes the name but has the old address, person X changes the old address and saves it. Person Y saves their data back which puts back the old address)

As long as you connect to the database, make your change and disconnect, you should be fine.

[Winx]

what are u writing this app in? i recommend implementing a disconnected data source as this will make ur app far more scalable. there are concurrency issues that u may have to sort out but it'll only push u towards developing more robust app's & that's always a good thing. :)