I'm debugging an issue with an Android application that seems to stem from missing data in its SQLite database. When I open the database using Android Debug Database, the data is shown. However, when I save the SQLite file to my computer using Android Studio's Device File Explorer and then open it up with a SQLite client, the data is missing.
Using Room to manage the SQLite db, and used both TablePlus and DB Browser for SQLite to view the db on my computer.
Room uses write-ahead logging (WAL). Much of the time, this means that the SQLite database consists of three files:
Whatever you named the base file
One with .wal
One with .shm
You need to copy all three if you wish to use the database elsewhere (e.g., desktop SQLite browser, backup/restore).
Related
So I want to view my db structure through some db browser application, but for that I need to get mydatabase.db file from application installed on emulator. I found this file through Device File explorer under data/data/package.com/mydatabase.db but when I open this file in some sqlite editor it shows that its empty no tables etc.. I'm using Room database so I'm thinking maybe room does something to this file that I can't open it because under database folder there is three files mydatabase.db, mydatabase.db-shm, mydatabase.db-wal which I never seen before when I was using just sqlite and maybe there is other ways to check structure of my db?
The -wal file is for write-ahead logging (WAL), which Room 1.1.0 enables. Try copying all three files, then opening the .db file.
WAL is a standard SQLite feature and has been around for years, so most up-to-date SQLite clients should be able to handle it.
I know about copying the database file solutoin,
How do I backup a database file to the SD card on Android?
Android backup/restore: how to backup an internal database?
Android backup/restore: how to backup an internal database?
in fact I was backing up my databases using this method, and up until a little while ago it was working perfectly.
until some multi-thread stuff made me use of enableWriteAheadLogging
now I have two more files near the database file with .db-wal and .db-shm extensions.
copying just the datbase file .db is not working as most of the times the file does not contain the latest database commits (which are available throw app itself) however when I copy three files together it seems to work fine (not quit sure, albeit)
as Sqlite people recommend, the best practice for backing up a sqlite database is to use backup api but can someone guid me on how I can use this api from inside an application, or even use sqlite .dump (How do I dump the data of some SQLite3 tables?) method from inside an app ?
So Which one is the best practice to back up a sqlite database from an android app?
1- Copy all the database-related files from the sandbox
2- Use sqlite Backup Api
3- Use sqlite .dump
4- any other method
The SQLite backup API is the only mechanism that works correctly with concurrent write accesses from other threads/processes. Which of course means that the Android database framework does not give you access to it.
If you are sure that there are not any active connections, you can just copy all files. (Leaving out journal or WAL files would lead to data corruption.) In the case of WAL, the -shm file
does not contain any permanent data and could be omitted.
The VACUUM INTO command introduced in SQLite version 3.27.0 (2019-02-07) can serve as an alternative to the backup API.
I have finished the notepad tutorial on the android site. I did this because i want to create a DB for my app. Once i finished i found out where the data is located in the DDMS. Then..
I downloaded the SQLite browser database i created a mini DB. Know i am trying to put this data into my project.
Can i put this new saved database file(i made with browser)into the notepad database file & and delete the old one. So when the emulator loads it will load my data.
Because i made a database with android notepad with all the code etc. with this SQLite browser i am thinking the code is done for me(table, columns,)
I guess am asking you is can i just make a full database with sql browser and just input it so how in my project.
Your database class needs to be specifc to your database, so you cannot just change databases on the back end and expect the handler class you wrote for the notepad tutorial on the front end to work properly with it.
That being said, you can create a handler to run your custom db. It's rather round-a-bout though. After you get the helper class created, you have to put your db into the assets folder. In your db helper you need code to copy the file out of assets to it's proper home in your applications data directory.
You can find instructions on how to set up your database so the Android framework can use it properly as well as code for copying it out of assets to your data directory here.
If I created a database using another application not through android runtime, let's say using 'SQLite Manager'(firefox extention), how can I then use that database (the .Sqlite file that is generated) in my android application?
Since the SQLite is native in the android not an outsider database.
you can do it by preparing database file(.sqlite) from Sqlite Manager(firefox extention) and then use it in android see example
Is there a better way in which android database from sd card of my android phone can be transferred to a web application using visual basic?
This Firefox addon can be of use.
You need to extract the schema for your database for your new. Bear in mind that SQL syntax for SQLite is different from MySQL... (I assumed you need to transfer your android db to MySQL web db)
Read this tutorial