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所以我試圖做一個簡單的閃存卡應用程序，它將存儲一個卡片列表，每個卡片組將包含閃存卡（每個閃存卡都有信息的正面和背面），但是我如何實現以便在創建新的卡片組時，我可以創建新的卡片並存儲在該卡片中？Android數據庫問題...如何連接2個數據庫？
我一直在SQLiteDatabase（對卡片組）有一個ID，字符串爲主題，字符串的甲板說明，但我不知道我怎麼可以連接數據表，以便每個卡組可以持卡。
繼承人我有的代碼。
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) > 0;
}
public boolean deleteCard(long rowId){
return mDb.delete(DATABASE2_TABLE, KEY_ROWID2 + "=" + rowId, null) > 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) > 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) > 0;
}
由於生病看看。 – 2011-05-04 21:49:07