Я пишу программу, которая может показывать данные, которые хранятся в базе данных в виде списка с помощью курсора. Но во время выполнения это заставляет меня закрыть. Я читаю logcat, но я не понимаю, что это за ошибка. Я даю свой код и logcat. Пожалуйста, помогите мне

код current_cart:

public class current_cart extends ListActivity {

    private ListView mainListView = null;
    CustomSqlCursorAdapter adapter = null;
    private SqlHelper dbHelper = null;
    private Cursor currentCursor = null;

    private ListView listView = null;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.current_cart);

        if (this.dbHelper == null) {
            this.dbHelper = new SqlHelper(this);

        }

        listView = getListView();
        listView.setItemsCanFocus(false);
        listView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
        //listView.setClickable(true);

        Button btnClear = (Button) findViewById(R.id.btnClear);
        btnClear.setOnClickListener(new OnClickListener() {

            public void onClick(View v) {
                Toast.makeText(getApplicationContext(),
                        " You clicked Clear button", Toast.LENGTH_SHORT).show();
              //  ClearDBSelections();
            }
        });

        new SelectDataTask().execute();

        this.mainListView = getListView();

        mainListView.setCacheColorHint(0);

    }

    @Override
    protected void onRestart() {
        super.onRestart();
        new SelectDataTask().execute();
    }

    @Override
    protected void onPause() {

        super.onPause();
        this.dbHelper.close();
    }

  //  protected void ClearDBSelections() {

      //  this.adapter.ClearSelections();

  //  }

    private class SelectDataTask extends AsyncTask {

        protected String doInBackground(Void... params) {

            try {

                current_cart.this.dbHelper.createDatabase(dbHelper.dbSqlite);
                current_cart.this.dbHelper.openDataBase();

                current_cart.this.currentCursor = current_cart.this.dbHelper
                        .getCursor();

            } 
            catch (SQLException sqle) 
            {

                throw sqle;

            }
            return null;
        }

        // can use UI thread here
        protected void onPostExecute(final String result) {

            startManagingCursor(current_cart.this.currentCursor);
            int[] listFields = new int[] { R.id.txtTitle,R.id.txtprice };
            String[] dbColumns = new String[] { SqlHelper.COLUMN_TITLE,SqlHelper.COLUMN_NAME_DESC };

            current_cart.this.adapter = new CustomSqlCursorAdapter(
                    current_cart.this, R.layout.single_item,
                    current_cart.this.currentCursor, dbColumns, listFields,
                    current_cart.this.dbHelper);
            setListAdapter(current_cart.this.adapter);

        }
    }

}

CustomSqlCursorAdapter code:

public class CustomSqlCursorAdapter extends SimpleCursorAdapter {
    private Context mContext;

    private SqlHelper mDbHelper;
    private Cursor mCurrentCursor;

    public CustomSqlCursorAdapter(Context context, int layout, Cursor c,
            String[] from, int[] to, SqlHelper dbHelper) {
        super(context, layout, c, from, to);
        this.mCurrentCursor = c;
        this.mContext = context;
        this.mDbHelper = dbHelper;

    }

    public View getView(int pos, View inView, ViewGroup parent) {
        View v = inView;
        if (v == null) {
            LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
            v = inflater.inflate(R.layout.single_item, null);
        }

        if (!this.mCurrentCursor.moveToPosition(pos)) {
            throw new SQLException("CustomSqlCursorAdapter.getView: Unable to move to position: "+pos);
        }

        CheckBox cBox = (CheckBox) v.findViewById(R.id.bcheck);


        cBox.setTag(Integer.valueOf(this.mCurrentCursor.getInt(0)));


        cBox.setOnCheckedChangeListener(new OnCheckedChangeListener() {

            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {


            }
        });

        TextView txtTitle = (TextView) v.findViewById(R.id.txtTitle);
        txtTitle.setText(this.mCurrentCursor.getString(this.mCurrentCursor
                .getColumnIndex(SqlHelper.COLUMN_TITLE)));
        TextView txtprice = (TextView) v.findViewById(R.id.txtprice);
        txtprice.setText(this.mCurrentCursor.getString(this.mCurrentCursor
                .getColumnIndex(SqlHelper.COLUMN_NAME_DESC)));

        return (v);
    }


}

SqlHelper код:

    public class SqlHelper extends SQLiteOpenHelper {
        private static final String DATABASE_PATH = "/data/data/com.example.bb/databases/";

        public static final String DATABASE_NAME = "ll";

        public static final String TABLE_NAME = "w";
        public static final int ToDoItems_VERSION = 1;

       // public static final String COLUMN_ID = "_id";             
        public static final String COLUMN_TITLE = "Good_Name";         
       public static final String COLUMN_NAME_DESC = "Good_UnitPrice";


        public SQLiteDatabase dbSqlite;
        private Context mContext;

        public SqlHelper(Context context) {
            super(context, DATABASE_NAME, null, 1);
            mContext = context;
        }

        @Override
        public void onCreate(SQLiteDatabase db) {
            createDB(db);
        }

        @Override
        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
            Log.w("SqlHelper", "Upgrading database from version " + oldVersion
                    + " to " + newVersion + ", which will destroy all old data");

            db.execSQL("DROP TABLE IF EXISTS w;");

            createDB(db);
        }

        public void createDatabase(SQLiteDatabase db) {
            createDB(db);
        }

        private void createDB(SQLiteDatabase db) {
            if (db == null) {
                db = mContext.openOrCreateDatabase(DATABASE_NAME, 0, null);
            }

            db.execSQL("CREATE TABLE IF NOT EXISTS w (Cart_ID INTEGER, Good_Name VARCHAR(50),Good_UnitPrice INTEGER (10),Quantity INTEGER);");
            db.setVersion(ToDoItems_VERSION);


        }

        public void openDataBase() throws SQLException {
            String myPath = DATABASE_PATH + DATABASE_NAME;

            dbSqlite = SQLiteDatabase.openDatabase(myPath, null,
                    SQLiteDatabase.OPEN_READWRITE);
        }

        @Override
        public synchronized void close() {
            if (dbSqlite != null)
                dbSqlite.close();

            super.close();
        }

        public Cursor getCursor() {
            SQLiteQueryBuilder queryBuilder = new SQLiteQueryBuilder();

            queryBuilder.setTables(TABLE_NAME);

            String[] asColumnsToReturn = new String[] {COLUMN_TITLE,COLUMN_NAME_DESC};

            Cursor mCursor = queryBuilder.query(dbSqlite, asColumnsToReturn, null,
                    null, null, null, null);

            return mCursor;
        }

       // public void clearSelections() {
         //   ContentValues values = new ContentValues();
          //  values.put(COLUMN_SELECTED, 0);
          //  this.dbSqlite.update(SqlHelper.TABLE_NAME, values, null, null);
       // }
    }

мой logcat:

12-19 14:36:02.999: E/AndroidRuntime(436): FATAL EXCEPTION: main
12-19 14:36:02.999: E/AndroidRuntime(436): java.lang.IllegalArgumentException: column '_id' does not exist
12-19 14:36:02.999: E/AndroidRuntime(436):  at android.database.AbstractCursor.getColumnIndexOrThrow(AbstractCursor.java:297)
12-19 14:36:02.999: E/AndroidRuntime(436):  at android.widget.CursorAdapter.init(CursorAdapter.java:169)
12-19 14:36:02.999: E/AndroidRuntime(436):  at android.widget.CursorAdapter.(CursorAdapter.java:117)
12-19 14:36:02.999: E/AndroidRuntime(436):  at android.widget.ResourceCursorAdapter.(ResourceCursorAdapter.java:52)
12-19 14:36:02.999: E/AndroidRuntime(436):  at android.widget.SimpleCursorAdapter.(SimpleCursorAdapter.java:78)
12-19 14:36:02.999: E/AndroidRuntime(436):  at com.example.nfc.CustomSqlCursorAdapter.(CustomSqlCursorAdapter.java:28)
12-19 14:36:02.999: E/AndroidRuntime(436):  at com.example.nfc.current_cart$SelectDataTask.onPostExecute(current_cart.java:110)
12-19 14:36:02.999: E/AndroidRuntime(436):  at com.example.nfc.current_cart$SelectDataTask.onPostExecute(current_cart.java:1)
12-19 14:36:02.999: E/AndroidRuntime(436):  at android.os.AsyncTask.finish(AsyncTask.java:590)
12-19 14:36:02.999: E/AndroidRuntime(436):  at android.os.AsyncTask.access$600(AsyncTask.java:149)
12-19 14:36:02.999: E/AndroidRuntime(436):  at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:603)
12-19 14:36:02.999: E/AndroidRuntime(436):  at android.os.Handler.dispatchMessage(Handler.java:99)
12-19 14:36:02.999: E/AndroidRuntime(436):  at android.os.Looper.loop(Looper.java:126)
12-19 14:36:02.999: E/AndroidRuntime(436):  at android.app.ActivityThread.main(ActivityThread.java:3997)
12-19 14:36:02.999: E/AndroidRuntime(436):  at java.lang.reflect.Method.invokeNative(Native Method)
12-19 14:36:02.999: E/AndroidRuntime(436):  at java.lang.reflect.Method.invoke(Method.java:491)
12-19 14:36:02.999: E/AndroidRuntime(436):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
12-19 14:36:02.999: E/AndroidRuntime(436):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
12-19 14:36:02.999: E/AndroidRuntime(436):  at dalvik.system.NativeStart.main(Native Method)