從Android中的SQLite數據計算總數

Question

我編寫了一個簡單的android應用程序，它接受數字數據的輸入並將其存儲在SQLite數據庫中，我如何計算總數並將其顯示給用戶。

下面是輸入

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;