我有一个（fillup_record）表我想要列出列名（Total_Cost）下的所有值，但是对于特定的汽车名称

Question

 public Double getCostt(String a) {
        openDatabase();
        Double price = null;
        Cursor cursor0=myDataBase.rawQuery("Select*FROM fillup_record WHERE Vehicle_Name='"+a+"'", null); //getting all values where vehicle name wi

  

在我的databasehelper类中，并为我的活动返回一个double值？提前感谢

        cursor0.moveToFirst();
        while (!cursor0.isAfterLast())
        {Cursor cursor = myDataBase.rawQuery("SELECT sum(Total_Cost) FROM fillup_record GROUP BY Vehicle_Name", null);
            price = Double.parseDouble(cursor.getString(3));
            cursor0.moveToNext();
        }
        cursor0.close();
        myDataBase.close();
        return price;
    }
}