I am implementing an android application and i can't figure out how to solve this problem
I'm trying to deploy an application with an existing SQLite database.
when user install application at the first time , Database will download but as trial version , with few records only , there are 10 feature extra than trial version when user select to buy one of them database should updated with new records from server , new records have the same schema of trial version database , so i want to insert purchased records to old database without delete old version and install new one with purchased feature
It seems that the most direct method would be to have separate text files containing the SQL commands to insert the data for each different upgrade.
Then your app can download said file, read the text file and execute the SQL commands contained therein, adding the data necessary.
You could either have the raw SQL in the file and use the rawQuery() method (somewhat dangerous IMO) or you can create a data structure to be read in by your app that takes the data and drops it into a method that can be parameterized like .insert().
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This is my first time working on a Xamarin App and I am new to the app development world so I need some help figuring out this process.
Currently I run a php web service that generates some SQL files that I run in DB Browser and I get a database file which I then put into my Assets and Resources Folder. Using each platform's API I copy the database into a writable folder and use that to run my queries.
I followed this really helpful tutorial and it worked perfectly fine.
https://medium.com/#hameedkunkanoor/creating-a-sqlite-databse-and-storing-your-data-in-your-android-and-ios-application-in-xamarin-2ebaa79cdff0 .
After the "initial" setup I store a timestamp in a local table and and the next time the user opens the app I pass that timestamp and retrieve data that is older than that timestamp. The I update that timestamp and continue the process. That data is sent back in JSON format and make the updates to the tables.
My only concern is if a new version were to come out where I add a new table or a new column which is not present in the current version of my Database, how should I take care of those update Web Service calls? Is there a way of monitoring my DB version? I read somewhere where I could just ignore the new data that is not present already, like table or columns, but I'm not really sure how to do that.
I also saw that if I call CreateTable on my current tables I could potentially update them?
Also for future reference each time I develop a new app would I need to regenerate a new database file to store in the assets/resources folder? Is there a more automated process for this? Along with monitoring the version of my database?
Any Help/Tutorials/Suggestions would be greatly appreciated.
You have to remember that CreateTable it's already doing the columns update for you, because internally it calls a method called MigrateTable which you can see here for further clarification: https://github.com/praeclarum/sqlite-net/blob/master/src/SQLite.cs#L562.
However you could have to handle more advanced modification to your database, like adding triggers or something similar.
In that case i suggest you to perform modifications manually.
In Xamarin Forms i've ended up with this:
https://gist.github.com/matpag/b2545cc22c8e22449cd7eaf6b4910396
Could not be the best strategy ever but seems to work for me.
Summarizing :
You have to save the database version in an internal flag of the SQlite database called user_version accessible with PRAGMA keyword.
Every time you get the database connection, you have to perform a check and see if the current database version is the same as the app last database version.
If not you need to perform a database update and set the new current version.
Reference here.
I have published my android app in google play store it works fine and perfect(my app first will go and create a sqlite DB using SQLiteOpenHelper class then the index.html page will be displayed) then i noticed that users with android version 2.3.6 have error when they install the app i solved the problem without changing or adding to the structure of the DB then after publishing the new version of my app without changing the version of the database my app will not show the index.html and i think it will keep trying creating the database and the user will just see the loading message only.
So do i have every time to change the database number even if i did not make any changes to my database structure to be published to google play store.
No, you only change the database version number to a higher version ONLY if you change the structure of the database or decide to automatically add data.
For example, you can start with version 1 with a database that contains only one table: let's call it User, and the table has a column called Username. You run the query to create the table on your onCreate method. Then you release the app.
Then you decide to add more features to the app, and implement a version of the app that did not require any database changes at all. Your db version stays 1.
Then on your next app version, you decide to add a column to the User table. So what you do, is increment the db version to 2, and then run the alter table statement on your onUpgrade method. Then you release the app.
I believe your issue lies somewhere else. Check your database data integrity and that it fits your app's model.
I know there are similar responses so I am going to make this very succinct. I am planning on developing an app which has 18 chapters and each chapter has 30 or 40 hymns. Now, Im planning on using an SQLite command, insert each hymn individually but after the insert, and after the APK file is generated, would the data on the database still be present? Or Does it need to inserted in on each install? What are my options?
If you use sqlite database for you app...every time the app is installed.. new database will be created(of course the old one will be deleted).. and so the hymns will be inserted on each install..(but once you install.. on running your app wont create new database and insertions..).. hope this is clear..
I am not Clear with your question..but if you r inserting data through your code..than on each installation your records would be inserted once..if you provide condition to do so for only once.
You have to code the insertion of the hymns at the start/launch of the application, so that the database is ready for retrieval for the application. But the next time, the application is started, check whether your database exists and has the hyms (size of database), if yes, dont populate the database again, if no, populate it. I hope you want to read from a file/array and insert the records to the database.Once you insert the records to the database, they are available for the reference until the application is uninstalled or the database is re-created. Sqlite database is a persistent storage. Now, Im planning on using an SQLite command, insert each hymn individually but after the insert, and after the APK file is generated, would the data on the database still be present? Yes it would be present. Once the application is installed, the code of database would be executed and the database would be created.
My suggestion to you is use the XML parsing to show the Hymens in place of sqllite. Simply create the xml file with the hymen tag then get the tag and show the data on screen.
I have a database that I built in SQLite browser, and it works fine. I launched an app with a prebuilt database and now I want to add more tables and data to that database.
I can get the app to launch the onUpgrade() method of the SQLiteOpenHelper. But the problem is, it's doing that EVERY time I use the helper.
I have it localized to, only on app launch, separating the upgrade command from the helper I used to retrieve data, but this is still a problem.
I have figured it out though, as I have been using the same database on my computer (the one that I'm editing) since version 1. So, whenever it writes the newer database onto the SD card it's showing version 1 even though I should be up to version 4 by now.
So, my question is, how can I manually edit the database version of the original database so that when it updates it isn't writing the old version number over the new one?
To manually update the version to 4 you execute the following SQL statement:
PRAGMA user_version = 4
Another way to change the version of your Sqlite Database. You can use DB Browser for SQLite:
Open the database file with "DB Browser for SQLite".
Change the "User Version" number to whatever number you want
Click the "Save" button
You can also set it via the setVersion SqlLiteDatabase method.
Source: http://developer.android.com/reference/android/database/sqlite/SQLiteDatabase.html#setVersion(int)
I have an SQLite database for my Android app that stores a copy of some data from another database on a server. When the user opens the app, I want to sync the local copy to the external master. The user may have been on the related website and inserted/updated/deleted data.
If it was just insert/update, timestamps could be used, but as they could delete data, I'm not sure how to go about checking for deleted rows.
So, what's the best way to tell what's changed and update the local copy?
I'd add a table to audit the deletes (containing key fields of the deleted records) and transfer that on sync, and after a successful sync clear the table down.
Hm, we are working on iOS project, which will sync it's database with server if server will respond what it have newer version.
Our server incrementally stores performed SQL and on request if compounds all those changes to specific date and gziped sends to the application, where my Objective-C wrapper execute SQL statement from downloaded file.
May be same approach will be good for you too.