Howto compare database query results

[bjf]

Hello.
I've created an app that pulls data from oracle database tables (lists outages from an electricity distribution management system).

What i now would like to do is create a service module for this, witch checks for new outages since the last time that the database has been checked.

Pretty much like that function that compares rss-files witch are on here somewhere.

Anyone with a suggestion how i can save the previous data map/rows?

I'm using httputils and JSON parser.

 

[Erel]

There are several possible solutions. The simplest one is to store the last successful time in a file and then fetch only entries newer than this time (assuming that there is an entry time field).

 

[bjf]

There are several possible solutions. The simplest one is to store the last successful time in a file and then fetch only entries newer than this time (assuming that there is an entry time field).

That´s pretty much exactly the way i was thinking about going
Exept i'm using the newest "outage ID" instead of a time.

i saw this thread:
http://www.b4x.com/forum/basic4android-getting-started-tutorials/6690-text-files.html#post38928

And i'm using the "SaveString" example to save the id to a file.
Had some problems reading back from the file though, but i hope i can solve that.

Any idea of how i could check for changes?
Meaning:
sometimes the outage is registred and sometime later a "description"-field is updated.
In this case it would of course not work to check for new outages since the id alredy been dowloaded.
But i would still like to get an update about the changed description/status

Can i save the whole map and compare it ore something like that?

Best regards
Björn

 

[Erel]

You can manually compare any data you like. However it will be very cumbersome to download all the database each time. The best solution is to add a "changelog" table to the database and then be able to only retrieve the latest changes.

 

[bjf]

Thank you, that would certainly be one possibility.

A related question regarding my app:
If there is changes in the database i'm using a notification to tell the user this.

As far as i can work out, when you click the notification you can tell it to access the main module, but is it possible to open a specific panel?

My outage check is just one of the "components" in my app.