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no database on my android phone

I am attempting to create a database in my Android app. It has worked, but when I restart the emulator I receive an error that indicates that my table does not exist. I have found that my "OnCreate" is not started and there is no directory on my sd card of my app? Can you help me find my mistake?
My code is:
public DatabaseVerwerker(Context context) {
super(context, database_naam, null, database_version);
}
public void onCreate(SQLiteDatabase db)
db.execSQL("CREATE TABLE IF NOT EXISTS variabel (key TEXT, value TEXT);");
)
And will the database still exists after close and open the app?
Greatings,
I hope it's my last post of android. it get's to mutch

Make sure your database has been created before you do your operation on database. The better way to create a database only used by your application is using openOrCreateDatabase. Here is the example.
CursorFactory cursorFactory = new CursorFactory() {
#Override
public Cursor newCursor(SQLiteDatabase db, SQLiteCursorDriver masterQuery,
String editTable, SQLiteQuery query) {
return null;
}
};
openOrCreateDatabase(DBNAME, MODE_PRIVATE, cursorFactory, new DatabaseErrorHandler() {
#Override
public void onCorruption(SQLiteDatabase dbObj) {
}
})

Thanks it works again. i must build the onUpdate function and trigger it.

Create new table in existing DB in separate SQLiteOpenHelper class

In my already created and deployed application, I've created a database MainDB, using a single class file which extended SQLiteOpenHelper, viz.
public class BaseSQLiteOpenHelper extends SQLiteOpenHelper {
private final static String DATABASE_NAME = "MainDB";
....
....
}
Issue is I've tied this class, too much to a particular functionality.
Now I'm adding a totally new module in application, which will also interact with DB, but with different new tables.
Issue is I can't use the same class, as it is conflicting in more than one way. And even if I redesign the code, it will only add complexity from functional/understanding point of view.
So, I've decided to use same DB, but different tables.
Now I've already created DB in BaseSQLiteOpenHelper class.
So, how can I create new tables in seprate class using same DB?
One approach is to use separate Database as well, Or,
Create my new table in onCreate() in BaseSQLiteOpenHelper class only (issue with this is mentioning new table in same class seems awkward, as this class has nothing to do with my new table).
Please suggest.
Thank You

First check the current database version for this database
private final static String DATABASE_NAME = "MainDB";
private static final int DATABASE_VERSION = 1;
public BaseSQLiteOpenHelper(Context context) {
super(context, DATABASE_NAME, null, DATABASE_VERSION);
}
and increment the database version(DATABASE_VERSION), and add your new table query in on Upgrade and oncreate method like below.
#Override
public void onCreate(SQLiteDatabase db) {
db.execSQL("old query no need to change");
db.execSQL("Create your new table here");
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
if (oldVersion < 2) {
db.execSQL("Create your new table here as well this for update the old DB");
}
}
Done!!!

Android Database

I am designing an application for an online exam. And I created a database using SQLite Browser and pulled it to Eclipse. In an emulator its working fine; it is able to retrieve and store data. But the problem comes when I place the .apk file on the mobile. On the mobile it's unable to retrieve the existing database. I am unable to bind the database file along with the .apk file, even after placing it in the assets folder.
Can anyone help?
Details:
Registration module
User Test module (display the questions from database)
Score submission module

How are you querying on database ?
The correct way is not to place a separate db in your code, but to create one dynamically. For e.g. the following code :
private static class DatabaseHelper extends SQLiteOpenHelper {
DatabaseHelper(Context context) {
super(context, DATABASE_NAME, null, DB_VERSION);
}
#Override
public void onCreate(SQLiteDatabase db) {
db.execSql("/*Put Create Table sqls here*/");
//onCreate will be called only once( when db doesn't exists for application, it creates here with the code)
}
#Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
}
}
Use a database helper class like this in your code.
Now whenever you want to query on your db you can do it like this :
dbHelper = new DatabaseHelper(ctx);
db = dbHelper.getWritableDatabase();
//Start querying on db.(if it is not created oncreate() of dbhelper will create it for you.
So simply put your initial db create,/insert statements in oncreate() of dbhelper

SQLite updation upon android app's update

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

Getting an Android Database Setup?

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);
}
}