Android database question... how to connect 2 databases?
<p>SO im trying to do a simple flashcard application which will store a list of decks, each deck will contain flash cards(each flash card has a front and back of information) but how can I implement so that when I create a new deck, I can create new cards that will be stored in that deck?</p>

<p>I been working on a SQLiteDatabase(for the deck of cards) which has an id, string for Subject, string for Description of deck, but I dont know how I can connect the data tables so that each deck can hold cards.</p>

<p>heres the code I have.</p>

<pre><code>public class CardsDbAdapter {

public static final String KEY_TITLE = "title";
public static final String KEY_BODY = "body";
public static final String KEY_ROWID = "_id";

public static final String KEY_FRONT = "front";
public static final String KEY_BACK = "back";
public static final String KEY_DECKNUM = "dnum";
public static final String KEY_ROWID2 = "_id";

private static final String TAG = "CardsDbAdapter";

private DatabaseHelper mDbHelper;
private SQLiteDatabase mDb;

/**
 * Database creation sql statement
 */
private static final String DATABASE_NAME = "cardData";
private static final String DATABASE_TABLE = "decks";
private static final String DATABASE2_TABLE = "cards";
private static final int DATABASE_VERSION = 2;
//================== DECKS TABLE ================================
private static final String DATABASE_CREATE =
    "create table decks (_id integer primary key autoincrement, "
    + "title text not null, body text not null);";

//================== CARDS TABLE =================================
private static final String DATABASE2_CREATE =
    "create table cards (_id integer primary key autoincrement, "
    + "dnum integer, front text not null, back text not null);";


private final Context mCtx;

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);
        db.execSQL(DATABASE2_CREATE);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        Log.w(TAG, "Upgrading database from version " + oldVersion + " to "
                + newVersion + ", which will destroy all old data");
        db.execSQL("DROP TABLE IF EXISTS decks");
        db.execSQL("DROP TABLE IF EXISTS cards");
        onCreate(db);
    }
}

/**
 * Constructor - takes the context to allow the database to be
 * opened/created
 * 
 * @param ctx the Context within which to work
 */
public CardsDbAdapter(Context ctx) {
    this.mCtx = ctx;
}

/**
 * Open the notes database. If it cannot be opened, try to create a new
 * instance of the database. If it cannot be created, throw an exception to
 * signal the failure
 * 
 * @return this (self reference, allowing this to be chained in an
 *         initialization call)
 * @throws SQLException if the database could be neither opened or created
 */
public CardsDbAdapter open() throws SQLException {
    mDbHelper = new DatabaseHelper(mCtx);
    mDb = mDbHelper.getWritableDatabase();
    return this;
}

public void close() {
    mDbHelper.close();
}


/**
 * Create a new note using the title and body provided. If the note is
 * successfully created return the new rowId for that note, otherwise return
 * a -1 to indicate failure.
 * 
 * @param title the title of the note
 * @param body the body of the note
 * @return rowId or -1 if failed
 */
public long createDeck(String title, String body) {
    ContentValues initialValues = new ContentValues();
    initialValues.put(KEY_TITLE, title);
    initialValues.put(KEY_BODY, body);

    return mDb.insert(DATABASE_TABLE, null, initialValues);
}
public long createCard(Integer dnum, String front, String back){
    ContentValues initialValues = new ContentValues();
    initialValues.put(KEY_DECKNUM, dnum);
    initialValues.put(KEY_FRONT, front);
    initialValues.put(KEY_BACK, back);

    return mDb.insert(DATABASE2_TABLE, null, initialValues);
}

/**
 * Delete the note with the given rowId
 * 
 * @param rowId id of note to delete
 * @return true if deleted, false otherwise
 */
public boolean deleteDeck(long rowId) {

    return mDb.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) &gt; 0;
}

public boolean deleteCard(long rowId){
    return mDb.delete(DATABASE2_TABLE, KEY_ROWID2 + "=" + rowId, null) &gt; 0;
}

/**
 * Return a Cursor over the list of all notes in the database
 * 
 * @return Cursor over all notes
 */
public Cursor fetchAllDecks() {

    return mDb.query(DATABASE_TABLE, new String[] {KEY_ROWID, KEY_TITLE,
            KEY_BODY}, null, null, null, null, null);
}

public Cursor fetchAllCards(long rowId){
    return mDb.query(DATABASE2_TABLE, new String[]{KEY_ROWID2, KEY_DECKNUM, KEY_FRONT, KEY_BACK},KEY_DECKNUM + "=" +rowId, null, null, null, null);
}
/**
 * Return a Cursor positioned at the note that matches the given rowId
 * 
 * @param rowId id of note to retrieve
 * @return Cursor positioned to matching note, if found
 * @throws SQLException if note could not be found/retrieved
 */
public Cursor fetchDeck(long rowId) throws SQLException {

    Cursor mCursor =

        mDb.query(true, DATABASE_TABLE, new String[] {KEY_ROWID,
                KEY_TITLE, KEY_BODY}, KEY_ROWID + "=" + rowId, null,
                null, null, null, null);
    if (mCursor != null) {
        mCursor.moveToFirst();
    }
    return mCursor;

}
public Cursor fetchCard(long rowId) throws SQLException {

    Cursor mCursor =

        mDb.query(true, DATABASE2_TABLE, new String[] {KEY_ROWID2,
                KEY_DECKNUM, KEY_FRONT, KEY_BACK}, KEY_ROWID2 + "=" + rowId, null,
                null, null, null, null);
    if (mCursor != null) {
        mCursor.moveToFirst();
    }
    return mCursor;

}
/**
 * Update the note using the details provided. The note to be updated is
 * specified using the rowId, and it is altered to use the title and body
 * values passed in
 * 
 * @param rowId id of note to update
 * @param title value to set note title to
 * @param body value to set note body to
 * @return true if the note was successfully updated, false otherwise
 */
public boolean updateDeck(long rowId, String title, String body) {
    ContentValues args = new ContentValues();
    args.put(KEY_TITLE, title);
    args.put(KEY_BODY, body);

    return mDb.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null) &gt; 0;
}
public boolean updateCard(long rowId, Integer dnum, String front, String back) {
    ContentValues args = new ContentValues();
    args.put(KEY_DECKNUM, dnum);
    args.put(KEY_FRONT, front);
    args.put(KEY_BACK, back);

    return mDb.update(DATABASE2_TABLE, args, KEY_ROWID2 + "=" + rowId, null) &gt; 0;
}
</code></pre>
