I am making a pokemon like game that will utilize SQLite DBs for storage and I'm trying to figure out how to best set it up.
I would like to have three tables:
One for all the "pokemon" and their stats
One for all the "pokemon" moves
One for the player's "pokemon"
I was thinking of having the app download the DB from my website so that I can add new "pokemon" and update/balance stats, but I want the player's "pokemon" list to stay the same unless they add/remove them from their teams.
Should I set up a DB with 2 tables for the "pokemon" and moves, and a second DB just for the player's "pokemon"? And how should I manage downloading/storing the DB? Currently I have it set up to download the sqlite DB to the SD card then have the app create a new SQLite DB passing the file location. What could I do to update the DB after I've made changes?
My advice is to change the way the database is being updated.
Instead of downloading the whole database as a file, as that seems to be what you're doing, a more suitable solution could be to have the application look for updates through a webservice and, if new updates are available, return them as XML / JSON / etc.
Your application could then parse the received data to generate SQL statements that would update the database without affecting current player stats.
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I have a phone application that uses a database of words and tests a user to see which words they know. I have a SQLite database with the words that I populate using a console application and this is then deployed as a resource to phones etc.
When the user runs the application then it stores pass fail data in the same database but in different tables.
When I update the application a fresh copy of the words database is installed on the phone and all the user data is lost.
How is this typically handled? Do phone applications that use SQLite have multiple databases with one being used to store user data and the other holding data which can be brought in when the application is first installed or updated?
If multiple databases are used then is it possible to create a look up from one database to the other?
Thanks in advance for any help, advice or links that point me in the right direction.
I would use a file (JSON, or plain text) to ship the words with the app. Then, when the app runs, it reads that file and adds the new words to the database. This won't affect the other tables.
Instead of having to deal with that, we hard code the values into a static method in code. Then at runtime, we see if there is any data in the table and, if not, we grab the hard coded data and do an insert.
In your case, I would also just add a version number of some kind so then, if the version was lower or the table was empty, you do a delete all and then insert your new static data.
I am pretty new to databases but I have an idea I'm trying to implement and I'm looking for some answers on if I'm going down the right path here.
I'm trying to create an app that displays locations in a list or on a map. The locations are going to be stored in a MySQL database hosted by Amazon Web Services. When the user opens the map portion of the app the database will be queried and the locations within the map view will be displayed. I figure the database won't be super big (around 10k locations) so I think it would be best to download the entire database and store it client-side on the users cell phone. There would have to be some kind of version check to determine if the user has the latest version of the database. Where would the version of the db be stored? Does the database or table automatically have a version number that increments automatically?
Second part of the question - is downloading the entire database (although small) a good idea? It seems like it would cut down on multiple database accesses per session and use less network traffic (anytime the user moves the map they would have to query for more locations within that area). I'm just trying to figure out if this is the best way to go about doing this since I'm brand new with databases. Thanks for any input.
Android has support for SQLite when it comes to embedded databases.
First you should check the compatibility between MySQL and SQLite SQL if you want to download the entire database.
Also, in android there is a class called SQLiteOpenHelper which has an onUpdate method that comes handy when one must update the database.
In my experience, I would recommend using a web service instead of downloading the entire database, mainly because of bandwidth and security issues.
I using SQLite as my database.
Using the app, the user can save some item on the database.
But I would like also to update the database from time to time.
The problem is how can I update the database without affecting the user inserted data and in a manner that it will download the new database online and not by updating the app itself.
Since my comment is large, I'll post it as an answer.
You won't find any tutorial showing exactly what you're trying to accomplish, because what you need is somewhat complex (but not difficult)
First approach:
You need your app to query some webservice to find out if there's a newer version of the database, and if there is, download it
The database must be saved in some temporary location, then you transfer all the users saved data to the new database, and finally replace the apps database with the new database (already updated with user's data)
Another approach would be:
Make your app query some webservice to find if the database needs to be updated.
If yes, download the SQL commands to modify the database structure.
With your help, I have successfully created a web page which has its own MySQL DB and then uses a JSON web service to pass the values my Android application.
The next stage is to copy them into a local SQLite DB so the phone does not require an internet connection to view the list.
I have successfully implemented code that creates a table, and inserts values into this table.
The problem is, I don't want it to necessarily re-write the whole DB at a time, which is the current idea to keep it current.
I might have things in the DB deleted or more things added, and want the local DB to reflect this.
What steps can I take to delete things that are no longer present in the MySQL DB in the SQLite one, and add new things?
Cheers
The best way to do this should be to have a date time column in your database and then just fetch the posts that are newer then the last time you fetched from the database, in your android app you could save an date time in your preferences
I'm sorry I missed that you wanted to delete items as well, than this probably isn't the best approach. Are you using the mySQL only for the API? Then you could probably mark posts as deleted inserted odd feeling them.
You can think this approach, parse your JSON response into objects of your data model and then create the content values holding that data model to work with the database in your device.
Once you have the content values, use a content resolver to work with your database and try an update of each data parsed from the JSON response (each content value), update method of the content resolver will return an integer value that tell us the number of rows updated in the database, if such number is 0 means that no data were in the database, so make an insertion, simply.
In that way you first search if the current data is present in the database, if it is, update it, if not, insert it.
We've got an android app and an iPhone app (same functionality) that use sqlite for local data storage. The apps initially come with no data, then on the first run they receive data from a remote server and store it in a sqlite database. The sqlite database is created by the server and the apps download it as one file, which is then used buy the apps. The database file is not very large by today's standards, but not a tiny one either - about 5-6 MB.
Now, once in a while, the apps need to refresh the data from the server. There a few approaches I can think of:
Download a new full database from the server and replace the existing one. This one sounds like the simplest way to deal with the problem were it not for a repeated 5-6 MB downloads. The apps do prompt the user whether they want to download the updates, so this may not be too much of a problem.
Download a delta database from the server, containing only the new/modified records and in some form information about what records to delete. This would lead to a much smaller download size, but the work on the client side is more complicated. I would need to read one database and, based on what is read, update another one. To the best of my knowledge, there's not way with sqlite to do something like insert into db1.table1 (select * from db2.table1) where db1 and db2 are two sqlite databases containing table1 of the same structure. (The full sqlite database contains about 10 tables with the largest one probably containing about 500 records or so.)
Download delta of the data in some other format (json, xml, etc.) and use this info to update the database in the app. Same as before: not to much problem on the server side, smaller download size than the full database, but quite a painful process to do the updates.
Which of the three approaches you recommend? Or maybe there's yet another way that I missed?
Many thanks in advance.
After much considerations and tries-and-errors, I went for a combination of options (2) and (3).
If no data is present at all, then the app downloads a full database file from the server.
If data is present and an update is required, the app downloads some database from the server. And checks the content of a particular value in a particular table. That value will state whether the new database is to replace the original or whether it contains deletions/updates/inserts
This turns out to be the fastest way (performance-wise) and leaves all the heavy lifting (determining whether to put everything into one database or just an update) to the server. Further, with this approach, if I need to modify the algorithm to, say, always download the full database, it would only be a change on the server without the need to re-compile and re-distribute the app.
Is there a way you can have a JSON field for each of the tables? For instance, if you got a table named users, have a column named "json" that stores the JSON for each of the users. In essence, it would contain the information the rest of the fields have.
So when you download the delta in JSON, all you got to do is insert the JSON's into the tables.
Of course with this method, you will need to do additional work in parsing the JSON and creating the model/object from it, but it's just an extra 3-4 small steps.
I will recommend approach 3, because app will download the json file more fast and local db will be updated more easily avoid overhead of more internet usages.
Just create a empty db initially according to server db and then regularly updated the same by fetching json