Android sqlite column sum?

Question

首先，我是一个编程新手，目前正在学习Android。这也是我在这里的第一个问题，所以如果有任何错误，请原谅。事情是我被困在如何获得数据库列的总数。下面是我从sqlite助手中检索数据的代码。

private void GetColumnTotal() {
    SQLHelper ColumnTOtal = new SQLHelper(this);
    try {
        ColumnTOtal.open();
        int total = ColumnTOtal.Total();
        ColumnTOtal.close();
        RemainingAmount.setText(""+total);
    } catch (SQLException e) {
        e.printStackTrace();
    }
}

下面是我的sqlite助手的代码。我把它贴出来，希望你们能帮助我。

public class SQLHelper {
public static final String KEY_ROWID = "_id";
public static final String KEY_MONEY = "SpendedMoney";
private static final String DATABASE_NAME = "BudgetDB";
private static final String DATABASE_TABLE = "BudgetTable";
private static final int DATABASE_VERSION = 1;
private final Context ourContext;
private SQLiteDatabase ourDATABSE;
private DBHelper ourHelper;

public SQLHelper(Context context) {
    ourContext = context;
}
public SQLHelper open() throws SQLException {
    ourHelper = new DBHelper(ourContext);
    ourDATABSE = ourHelper.getWritableDatabase();
    return this;
}
public void close() {
    ourHelper.close();
}
public long createEntry(String money) {
    ContentValues cv = new ContentValues();
    cv.put(KEY_MONEY, money);
    return ourDATABSE.insert(DATABASE_TABLE, null, cv);
}
public String getData() {
    String[] columns = new String[]{KEY_ROWID, KEY_MONEY};
    Cursor c = ourDATABSE.query(DATABASE_TABLE, columns, null, null, null, null, null);
    String result = "";

    int iRow = c.getColumnIndex(KEY_ROWID);
    int iName = c.getColumnIndex(KEY_MONEY);
    for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()) {
        result = result + c.getString(iRow) + " :- " + c.getString(iName) + "n";
    }
    return result;
}
public int Total() {
    Cursor cur = ourDATABSE.rawQuery("SELECT SUM(SpendedMoney) FROM BudgetTable", null);
    if (cur.moveToFirst()) {
    }
return cur.getInt(0);
}

private static class DBHelper extends SQLiteOpenHelper {
    public DBHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        db.execSQL("CREATE TABLE " + DATABASE_TABLE + "(" +
                        KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
                        KEY_MONEY + " TEXT NOT NULL);"
        );
    }
    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        db.execSQL("DROP TABLE IF EXISTS " + DATABASE_TABLE);
        onCreate(db);
    }
}

解决! !谢谢每一个人。还有那个对我的问题投反对票的人…:)

Answer 1

此错误信息与SQLite无关。在其他地方，您在期望字符串资源id的地方使用0。例如，您可以在TextView而不是setText(CharSequence)上使用setText(int)显示结果。