SUM sqlite column values in android

I must get the sum of the values of a column, but I get the number of the rows of the table.

Here is the code that I use to retrieve the sum value:

Cursor c=sqLite.getPrezzoTotaleCarrello();

        while(c.moveToNext())
        {
            prezzoTotaleCarrello.setText(c.getString(c.getColumnIndex("Somma_totale"))); 
            Log.d(prezzoTotaleCarrello.getText().toString(),"Visualizziamo");
        }

Here is the code of the getPrezzoTotaleCarrello() method:

public Cursor getPrezzoTotaleCarrello()
    {
        String query = "select SUM(Prezzo_totale) AS Somma_totale  from Carrello";

        return getReadableDatabase().rawQuery(query, null);
    }

The method getPrezzoTotaleCarrello is inside a class extending SQLiteOpenHelper.