запрос к базе данных для преобразования единиц

Question

Выше приведен код, который позволит мне конвертировать между двумя разными единицами, однако, добавив selection, selectionArgs и projection в запрос, который вылетает при нажатии кнопки ввода.

DatabaseHelper dbhelper = new DatabaseHelper(getContext());
                    SQLiteDatabase database = dbhelper.getReadableDatabase();
                    String[] projection = {DatabaseContract.FeedEntry.COLUMN_NAME_Ratio};
                    // filter results WHERE column unit from and column unit to = input and result to string
                    String selection = DatabaseContract.FeedEntry.COLUMN_NAME_UNIT_FROM +
                            " = ?" + " AND " + DatabaseContract.FeedEntry.COLUMN_NAME_UNIT_CONVERTING_TO
                            + " = ?";
                    String[] selectionArgs = {fromText.getText().toString(), toText.getText().toString()};

                    // the table to the query, the array of columns to return, the columns for the WHERE clause,
                    // the values for the WHERE clause, dont group the rows, dont filter by rows, not to be sorted
                    Cursor cursor = database.query(DatabaseContract.FeedEntry.TABLE_NAME, null, null,
                            null, null, null, null);

                    ArrayList<String> itemIds = new ArrayList<>();
                    while (cursor.moveToNext()){
                        String itemId = cursor.getString(cursor.getColumnIndexOrThrow
                                (DatabaseContract.FeedEntry.COLUMN_NAME_Ratio));
                        itemIds.add(itemId);
                        // to check the items present in the array list
                        Log.e("Array list",itemIds.toString());
                    }
                    cursor.close();

                        int toBeConverted = Integer.parseInt(input.getText().toString());
                        double findRatio = Double.parseDouble(itemIds.get(0));
                        double conversion = toBeConverted * findRatio;
                        result.setText(String.valueOf(conversion));

                }