java 安卓 sqlite没有这样的表

Question

我使用的是一个预制数据库，当我试图更新一行时，似乎出现了一个错误。logcat的确切错误是：（1）没有这样的表：AUD。下面是我的dbhelper类的外观：

public class DataBaseHelper extends SQLiteOpenHelper {
private static String TAG = "DataBaseHelper"; // Tag just for the LogCat window
//destination path (location) of our database on device
private static String DB_PATH = "/data/data/com.example.simplecurrency3/databases/"; 
private static String DB_NAME ="Currencies";// Database name
private SQLiteDatabase mDataBase; 
private final Context mContext;

public DataBaseHelper(Context context) {
super(context, DB_NAME, null, 2);// 1? its Database Version
if(安卓.os.Build.VERSION.SDK_INT >= 17){
   DB_PATH = context.getApplicationInfo().dataDir + "/databases/";         
}
else
{
   DB_PATH = "/data/data/" + context.getPackageName() + "/databases/";
}
this.mContext = context;
}   

public void createDataBase() throws IOException {
//If database not exists copy it from the assets

boolean mDataBaseExist = checkDataBase();
if(!mDataBaseExist)
{
    this.getReadableDatabase();
    this.close();
    try 
    {
        //Copy the database from assests
        copyDataBase();
        Log.e(TAG, "createDatabase database created");
    } 
    catch (IOException mIOException) 
    {
        throw new Error("ErrorCopyingDataBase");
    }
}
}
//Check that the database exists here: /data/data/your package/databases/Da Name
private boolean checkDataBase()
{
    File dbFile = new File(DB_PATH + DB_NAME);
    //Log.v("dbFile", dbFile + "   "+ dbFile.exists());
    return dbFile.exists();
}

//Copy the database from assets
private void copyDataBase() throws IOException
{
    InputStream mInput = mContext.getAssets().open(DB_NAME);
    String outFileName = DB_PATH + DB_NAME;
    OutputStream mOutput = new FileOutputStream(outFileName);
    byte[] mBuffer = new byte[1024];
    int mLength;
    while ((mLength = mInput.read(mBuffer))>0)
    {
        mOutput.write(mBuffer, 0, mLength);
    }
    mOutput.flush();
    mOutput.close();
    mInput.close();
}

//Open the database, so we can query it
public boolean openDataBase() throws SQLException
{
    String mPath = DB_PATH + DB_NAME;
    //Log.v("mPath", mPath);
    mDataBase = SQLiteDatabase.openDatabase(mPath, null, SQLiteDatabase.CREATE_IF_NECESSARY);
    //mDataBase = SQLiteDatabase.openDatabase(mPath, null, SQLiteDatabase.NO_LOCALIZED_COLLATORS);
    return mDataBase != null;
}

@Override
public synchronized void close() 
{
    if(mDataBase != null)
        mDataBase.close();
    super.close();
}

@Override
public void onCreate(SQLiteDatabase db) {
    // TODO Auto-generated method stub

}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    // TODO Auto-generated method stub

}

}

当我尝试更新一行时：

        Context context = getActivity().getApplicationContext();
        DataBaseHelper dbHelper = new DataBaseHelper(context);
        dbHelper.openDataBase();
        SQLiteDatabase db = dbHelper.getWritableDatabase();         
        db.execSQL("UPDATE AUD SET AUD = 2.0")

Answer 1

您从未调用过createDataBase()方法！您可以将其放入onCreate()方法中

祝你好运

Answer 2

不要更新行，而是首先使用以下查询检查表是否真的存在

SELECT name FROM sqlite_master WHERE type='table'