android - 从android中的SQLite数据计算总数

Question

我正在编写一个简单的 android 应用程序，它接受数字数据输入并将其存储在 SQLite 数据库中，我如何计算总数并将其显示给用户。

输入代码

String title = expenseTitle.getText().toString();
        String amount = expenseAmount.getText().toString();
        Date date = new Date( datePicker.getYear() - 1900, datePicker.getMonth(),  datePicker.getDayOfMonth());
        String dateString = date.toString();

        Database myDb = new Database(getApplicationContext());
        SQLiteDatabase expenseDB = myDb.getWritableDatabase();

        ContentValues contentValues = new ContentValues();
        contentValues.put(Database.EXPENSE_TITLE, title);
        contentValues.put(Database.EXPENSE_AMOUNT, amount);
        contentValues.put(Database.EXPENSE_DATE, dateString);
        expenseDB.insert(Database.TABLE_NAME, null, contentValues);

Answer 1

Cursor c = expenseDB.rawQuery("select sum(" + Database.EXPENSE_AMOUNT + ") from " + Database.TABLE_NAME;