Help with AVG in Query with Left Join

I need help to write sql query to know avg of position.

SELECT p.date_add, p.pozycja, f.nazwa FROM fraza f
LEFT JOIN pozycja p ON f.id = p.parent_id
WHERE f.parent_id = 101 AND p.date_add BETWEEN '2010-12-01' AND '2011-01-01'
ORDER BY f.nazwa DESC, p.date_add ASC
LIMIT 1000

now i got something like this:

date_add   |  pozycja(position)  | nazwa(name)
2010-12-01          12               example1
2010-12-01          12               example2
2010-12-01          12               example3
2010-12-01          12               example4
2010-12-01          12               example5
2010-12-02          36               example1
2010-12-02          36               example2
2010-12-02          36               example3
2010-12-02          36               example4
2010-12-02          36               example5

how to get now something like this:

     posisiton    | name
        24         example1
        24         example2
        24         example3
    开发者_JS百科    24         example4
        24         example5

its avg of month name's position

SELECT p.date_add, avg(p.pozycja) as avg_pozycja, f.nazwa FROM fraza f
LEFT JOIN pozycja p ON f.id = p.parent_id
WHERE f.parent_id = 101 AND p.date_add BETWEEN '2010-12-01' AND '2011-01-01'
GROUP BY f.nazwa
ORDER BY f.nazwa DESC, p.date_add ASC