I'm trying to create some sort of backup & restore function in my app. Before that, I've been reading for a while to understand if it's possible to achieve, but I found out this question:
Sqlite DB Android Backup/Restore
The only other way I could see to do it, would be to read the actual contents of the DB and generate a file containing the SQL which which it can be restored from, this is obviously a more complex and doesn't offer any advantages to justify this complexity.
This answer, I think, is the best way to accomplish that; not explorting the .db file, but exporting queries.
You know; when you export a SQL data from mysql, you get a file which contains all the queries that creates the structure and queries that fill the structure with data.
That's what I'm trying to mimic; generate a file which contains sql queries from a .db file.
Do you guys think it's possible, I mean, is there any builtin method to achieve that?
Otherwise, if its too hard to handle, how do you manage to avoid what this user (https://stackoverflow.com/a/10842043/1943607) is talking about?
So, I disabled WAL with "PRAGMA journal_mode = DELETE" and then I was able to view the database in the browser and able to restore it on my test device fine.
That previous part, I can't understand it. Is this a configuration you set to sqlite?
Thanks
I haven't actually tried this with sqlite, but with mysql you could do things like create "dumps" of your database. Those dumps contained exactly what you describe: a set of queries that, when executed together, recreate the database, including the contents.
Judging from the "sqlite3" documentation found at http://www.sqlite.org/sqlite.html (especially the "Converting An Entire Database To An ASCII Text File" section), you can do the same for sqlite. Since you can execute shell commands from a java application (using Runtime.getRuntime().exec() methods), and you are the "owner" (Linux user id) of the database, you should be able to run this "sqlite3 .dump" command even on a non-rooted device. I have never seen an Android device without the sqlite3 tool installed, so the command should always be available.
Moreover, since dump file is just a text file, you should be able to prepend any PRAGMA's to it that are required for compatibility (like the one you quoted).
I haven't tested any of this, but just wanted to think with you on this interesting topic.
An sqlite database is just a file so you could copy the file but I think you may have problems with permissions in android preventing you from accessing the database.
A better solution IMO would be to sync your data to an external website.
Using a combination of a custom sync adapter and the account manager with a website or web service that has a RESTfull api to receive and send the synced data would be the most reliable approach.
http://developer.android.com/training/id-auth/identify.html is a great introduction to setting up the account manager.
And for a custom sync adapter this is a great starting point.
http://www.c99.org/2010/01/23/writing-an-android-sync-provider-part-1/
and http://www.c99.org/2010/01/23/writing-an-android-sync-provider-part-2/
And finally an explanation of how it all fits together
https://sites.google.com/site/andsamples/concept-of-syncadapter-androidcontentabstractthreadedsyncadapter
The above approach would enable a user to switch phones and retain data at the same time and the data would always be up to date (providing you sync at the appropriate times.
It seems like a lot of work as you will need to set up a web service but it is the BEST way to make sure data is kept safe and secure and can be restored and backed up at any point.
For a web service there are lots of options available to you including cloud services such as Google docs or writing your own website. Ruby on Rails is a great solution for developing your own site as you get a full RESTfull api out of the box and it;'s dead easy to secure/lock down a rails site to authorised users only with a couple of lines of code and with Heroku you can get free hosting.
As usual with Android development the simplest of requirements actually ends up being the most difficult to implement but where data safety is paramount then it's worth the effort to do it properly.
The question is too open to answer simply because the changes that may apply to the db file content are open and one can't guarantee a specific behavior .
On the positive side sqlite project is an open source and the format of the DB file is specified Here
After taking a look there, it seems very possible/not too complicated to parse any DB file looking for Data Only and write it/dump it to another functional db file.
I believe this is the fastest and cleanest solution to the issue in hand.
so to wrap up:
Copy DB file everytime you want to back it up.
When you want to restore create a new DB using Android APIs.
Parse the data from the backed up file and write them to the newly created DB.
P.S:
regarding how to use
PRAGMA journal_mode = DELETE
Simply use db.exec("PRAGMA journal_mode = DELETE"); when creating the DB
Related
I'm really new to programming apps - so this question might sound a bit strange:
I'm trying to program an app in android studio, where people can upload different things (basically strings and links put together in some kind of "package") and other peoble can then decide what "packages" they want to add inside their app. However after downloading, this data should be stored on their device and not just in the memory of the phone so that they can use it after restarting the app (and also if theres no internet connection). Do you have any idea what would be the best way to store this data both on the phone and in a database and how to synchronize the data on the phone with the selected data from the database. I really dont want to know how to do this exactly but would rather like some basic ideas and maybe you could tell me what kinds of stuff i should learn in order to succeed and what kind of database would be best here (firebase, MYSQL,..)?
Thanks a lot,
Andi
First of all you should decide what DB you are going to use.
In my opinion all RDBMs are good, but using Sqlite in order to achieve best performance on android devices is a good idea.
In your case you need server-side DB and application too.
(Depend on the scenario and framework you use can be different (sql,mysql,PostgreSQL,oracle,...)).
About how to sync local database with server-side you can download new DB from server and replace it with previous one, if you need previous user data you can have 2 different table and update one by downloading it from server, and save id or any identical row from specific package that already saved by user.
These are some question has been already answered in Stackoverflow
java - How to update table in sqlite?
java - SQLite in Android How to update a specific row
Create SQLite database in android
If you are talking about local databases. Go for Realm or look up a good ORM on github (Object relational mapping, you dont have to write SQL queries explicitly) .
I would suggest Realm which is very fast and user friendly.
I'm starting to build a new Android application which will help me to manage material movements in a warehouse. I would like to use use a database for the following applications:
A table that will be managed from a server (my PC probably) to add or delete new users.
Also, there must be another table that will be managed by users. This table will be used to add or delete materials from the warehouse.
I'm not sure what kind of database to use. I have some knowledge of using MySQL Workbench to create and manage databases. However, I've read the SQLite is better for Android applications. Can you please help me to choose which one will be the best for my application?
Thanks
If the databases run on the android device (which I guess they do not from the description) SQLite is probably the way to go. I like this tutorial but there are millions out there.
If they run somewhere ales (server) you can choose whatever system you are comfortable with since you will have to implement some protocol to communicate between mobile device and server anyway (most people would use HTTP/REST for that, but again, you can do that in a million ways)
SQLite is indeed better for Android applications.
In terms of preloading tables, schemas, and data into a Sqlite database, you can use the SQLiteManager firefox extension to do it.
Or, if you're too lazy to care about what types of database to use, might as well use ORMLite for Android to manage your tables and schemas within your Android application.
As for your server, you'll need to expose the API so that you can do HTTP/RESTful operations on it. You can choose whatever web applications that you prefer.
In my android projects I need database to store data for offline usage.
For that I am looking at two options 1)Creating the empty db and copying it to asset 2)Creating the db via code
which option will be good as my app is handling secure data.
weather it will cause any security vulnerability if we store the db structure in asset folder as it will be easily available if we extract .apk file.
Thanks for your support
If your database has something you don't want your legitimate user to see, look for a new project because you cannot attain that. Using a static database in the APK is as you know, easily viewable, but creating it from your app also leaves something that is viewable. You could encrypt the contents, but then you have the problem of how you store the key in a way the user cannot access -- so you really haven't solved anything.
Back to your original question though -- is the data static, or is your application ever going to make changes to it? If the data is static, providing a pre-populated database is fine. If the application is intended to be able to make changes though, you are much better served by letting the application create and manage updates on the database, its schema, and its contents. Following Google's examples will get you there.
I need to ship an app that uses read-only access to several preexisting SQLite3 DB's that each are a couple of 100MB's, total combines size > 1GB. The databases are created on a Mac, and are currently used in a shipping iOS app. I am pretty proficient in Java, but new to Android.
This leads to the following questions:
1) Will I need to modify the databases? I only plan to use them with SQLiteDatabase::rawQuery queries, so no nee for bindings and metadata I hope.
2) It it really correct that even if the DB's will only be used as read-only, I'll have to copy them out of the app bundle or download them to user directory on first start-up?
3) The queries can be slow. I want to run them in a thread and provide data via a callback. Is this done the way it's done in normal Java (Runnable/Thread), or will I have to use another method?
4) Is there anything else that's obvious to the Androidan that I have clearly missed?
1) No, it should work fine.
2) Yes, if you want to ship an APK that is over 50Mb you will need to use an expansion file.
3) For easy background tasks with a call back you could use an ASyncTask.
for a decent example of a sqlite helper class look here
you shouldnt need to edit the database. my sqlite databases work the same wether I access them via sqlite3 or with the android my sqlite helper class
once you copy them you can read and write
not really sure about this answer. i will say though that the database helper class above seems to work just fine (fast) but my db is smaller (500kb)
dont think so
I have an app that stores a sqlite database in the usual place. ie: data/data/com.blah.blah/databases. I wish to remotely locate the SQLITE database and read from and write to it. I wonder if there is a way to do it without using the Oracle Mysql option. Is there a way to just change the default location to a folder on a website. Thanks in advance. If so how do I do it. I cant find any tuts or books that explain how its done.
SQLite isn't a remote database implementation. That is kind-of part-of white it is called SQ*Lite*. :) It is for doing SQL databases based on local files, without taking the big additional overhead of having some remoteable service protocol sitting between you and the database.
There are all kinds of options for interacting with remote data stores, not just MySQL - PostgreSQL, etc. You can use whatever of those you want. You can then have on the device just the client code you need to communicate with the remote data store. It doesn't make sense for Android to supply any complicated/sophisticated here built-in, though, since exactly what you want is going to depend mostly on what you are using on your back-end server.