Typically, for a WinForm or a Web App, I create the database and tables through the RDBMS or through a separate install process. However, I haven't seen anything of the sort in Android. All the examples I've seen have the database creation scripts embedded in an activity like this.
The best thing I can come up with now is to call a method from the data access constructor to check whether the database is installed - if not - install it. However, this seems like a lot of overhead to me.
What's the cleanest way to execute a android database install and then forget about it?
When using SQLLiteOpenHelper (http://developer.android.com/reference/android/database/sqlite/SQLiteOpenHelper.html), the onCreate method will be called only if the database doesn't exist. onUpgrade will be called when a new version of the database is introduced.
IF the database already exists, and no version upgrade occured, these methods won't be executed.
There is no need for implementing if-else checks in your activity.
private static class DatabaseHelper extends SQLiteOpenHelper
{
DatabaseHelper(Context context)
{
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
#Override
public void onCreate(SQLiteDatabase db)
{
db.execSQL(DATABASE_CREATE);
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion,
int newVersion)
{
Log.w(TAG, "Upgrading database from version " + oldVersion + " to " + newVersion);
db.execSQL(DATABASE_UPGRADE);
}
}
Related
I have uploaded an apk (version 1.0) with 22 tables in SQLite Database on Google Playstore.
Now i want to update database with 36 tables in new version (version 2.0) of application.
I am storing datebase at default location so when i press "Clear
data" in Application Manager, database is gonna deleted.
I just want to know how to delete old database (same as clear data) when user update new version?
Update:
If is there any solution for clear data while updating application from play store then also answered me.
Your help would be appreciated.
Thanks.
you can use this method to delete your database.
context.deleteDatabase(DATABASE_NAME);
You can also use this method to find your database path first and then delete that.
File myDb = context.getDatabasePath(DATABSE_NAME);
Boolean isDelete = myDb.delete();
The other solution is , if you want to update your database then just change your version number of database. onUpgrade() will automatically get called and your old database will be deleted and new database will be created.
Finally done with simple solution:
/** UPGRADE DATABASE **/
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
Log.i(TAG, "Database Version: OLD: "+ oldVersion + " = NEW: "+newVersion);
if(context.deleteDatabase(DATABASE_NAME))
Log.i(TAG, "Database Deleted....");
else
Log.i(TAG, "Database Not Deleted..");
}
Nice Question. Just follow the steps.
1) There are two methods that you override on Your Helper class
#Override
public void onCreate(SQLiteDatabase db) {
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
if(oldVersion!=newVersion){
// Remove all old tables and crate new ones
}
}
2) create an object of Helper class.
MyOpenHelper dbHelper = new MyOpenHelper(this,"dbname", 1);
3) Now just increase the database version when you want to change the database.(Third argument in MyOpenHelper class. "1" is a database version).
4) When database version changes it will give you a callback in onUograde() method.
5) Remove all tables in onUpgrade() method and create new ones.
6) That's it.
EXPLANATION :
Your app version 1.1 is on google play and your database version is "1". Now you want to upload version 1.2 with new database. Just set database version "2" in your helper file. And check the the oldVersion and newVersion in onUpgrade() method if both are not same that means application updating and remove old tables and create new ones.
If you are using SQLiteOpenHelper just delete your tables in your onUpgrade method and recreate all your tables again. You should have not problems at all.
Check this out.
Hope it helps
Note: Be careful with database versions, if you are playing with your database numbers make sure you have the right number as your oldVersion or it will not work properly when you update your google play.
The obvious solution is to delete the old DB file when onUpgrade() is called and copy the new version over. Too bad it does not work. You get an error something like this:
Caused by: android.database.sqlite.SQLiteReadOnlyDatabaseException: attempt to write a readonly database (code 1032)
SQLiteLog﹕ (1032) statement aborts at 4: [PRAGMA user_version = 2]
SQLiteLog﹕ (28) file unlinked while open: /data/data/my.package/databases/my_db.db
You don't need to delete the database, just copy over it using the method you've alady defined (copyDataBase), like this:
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
Toast.makeText(myContext, "onUpgrade called!", Toast.LENGTH_LONG).show();
if (oldVersion < newVersion) {
Log.v("Database Upgrade", "Database version higher, upgrading");
try {
copyDataBase();
} catch (IOException e) {
throw new Error("Error upgrading database");
}
}
}
wrok for me, thank
I am developing a database application and I am stuck up at one place.
The scenario is: I have a database and I am maintaining the version of the database.
It is the same as that of the application version.
Now I am implementing the database in version 1. There are 3 tables getting created in version 1. In version 2, I am upgrading the database by adding one more table. Hence, the query is in the upgrade().
Now, what if the user installs version 2. The onUpgrade() will not get called because there is no database. Hence, the onCreate() will be called and the consequence will be it will create only 3 tables.
I was thinking to call the onUpgrade() explicitly in the onCreate(). But many developers on stackoverflow have suggested not to call it explicitly.
I am completely stranded.
Thanks in advance.
I know it's an old post, you have certainly found a solution, but I find the question valid (upvoted) and as it did not receive an answer, here are my 2 cents:
Calling onUpgrade() from onCreate() should work (I did not test it), but there is a better way to organize you helper (see snippet hereafter). The key point is that both those methods are just entry points.
public class SampleDBHelper extends SQLiteOpenHelper {
private static final String DB_NAME = "mydatabase";
private static final int DB_VERSION = 2;
public SampleDBHelper(Context context) {
super(context, DB_NAME, null, DB_VERSION);
}
#Override
public void onCreate(SQLiteDatabase db) {
updateDatabase(db, 0, DB_VERSION);
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
updateDatabase(db, oldVersion, newVersion);
}
private void updateDatabase(SQLiteDatabase db, int oldVersion, int newVersion) {
if (oldVersion < 1) {
// Create 3 initial tables
}
if (oldVersion < 2) {
// Create the new table
}
}
}
The advantages of this kind of helper:
You never need to change onCreate() and onUpgrade() methods, only updateDatabase().
For each new version, you just need to :
increment DB_VERSION
add a new section if (oldVersion < N) { // do the upgrade }.
Credit : Strongly inspired from Head First Android Development, Dawn and David Griffiths, O'Reilly, 2015
I add one more table to my app's database.
However, if I upgrade my app without clearing its data, the new table doesn't seem to be added automatically.
Therefore, some code that need to retrieve data from the new table fail.
Is it possible to add new tables automatically on app upgrade?
Please implement onUpgrade (SQLiteDatabase db, int oldVersion, int newVersion) method.
There is an Android helper class to manage database creation and version management using an application's raw asset files.
Have a look at this :
https://github.com/jgilfelt/android-sqlite-asset-helper
Yes there is a method onUpgrade
add you code there and increase database version if your version is higher than the previous
onUpgrade is fired and the your code will execute which you write to add table
sample
Remember increasing you version code in super call
class Database extends SQLiteOpenHelper
{
public Database(Context _myContext)
{
super(_myContext, DB_NAME, null, DB_VERSION_CODE);
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{
if(oldVersion > newVersion)
{
// create a new table what you want to create you can also check the existence of the table
}
}
}
I have an app released on the android market which uses sqlite and displays data. I want to know if I am sending an update for the app by adding features, should I upload a new database? What happens when users already having my app, click on update? Will the database update on its own? If the users are downloading my app for the first time, they will certainly get the new db content...but what about the existing users?? I want to know if I have to explicitly update the database in the program
When you create your new version... If you change the version of the database... The onUpgrade function will run on all the existing users:
public static final int dbVersion = 2;
protected static class DatabaseHelper extends SQLiteOpenHelper {
public DatabaseHelper(Context context) {
super(context, dbName, null, dbVersion);
}
#Override
public void onCreate(SQLiteDatabase db) {
//create tables
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
//what do you want to do to existing users? maybe recreate?
}
}
Why not create the sqlite database through code? That way your updates can update the SQL on the database (alter columns, add rows) without affecting the users existing data.
If you are changing database's attributes then on updation it will create problem and if the database's attributes are same then it will not have any effect...
You may use android.database.sqlite.SQLiteOpenHelper class it supports versions and migration mechanism
I am trying to upgrade a certain table by adding a column to a Sqlite table in my android app.I have added an alter table statement in the onUpgrade method of my DBHelper.
Here are the problems that I am seeing
I changed the value of Database version from 1 to 2, so ideally now the onUpgrade should get called.It does get called, but it gets called everytime I instantiate the class.As a result I get a column already exists error.
Here is the onUpgrade method
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion,
int newVersion)
{
Log.d("old Version",oldVersion+"");
Log.d("New Version",newVersion+"");
db.beginTransaction();
try
{
String DATABASE_UPGRADE;
DATABASE_UPGRADE="alter table "+DATABASE_TABLE_MESSAGES+" ADD COLUMN "+ IS_READ+ " integer DEFAULT 0;";
db.execSQL(DATABASE_UPGRADE);
Log.d("upgrade", "Successful");
db.setTransactionSuccessful();
}
finally
{
db.endTransaction();
}
}
}
I am wondering why the onUpgrade gets called each time!!!
In the constructor of your database helper are you correctly passing the new version number?
EDIT: should look like this
DatabaseHelper(Context context)
{
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
and DATABASE_VERSION should be 2.