Table name : attributes
Only 3 fields: userid, attributeid, value

Table before required UPDATE statement :
userid attributeid value
1 14 2000-11-29
1 33 NULL
1 34 NULL
2 14 2002-06-30
2 33 NULL
2 34 NULL
...

How do I update it to get this result :
userid attributeid value
1 14 2000-11-29
1 33 11 (or November, ...)
1 34 29
2 14 2002-06-30
2 33 06 (or 6, or June, ...)
2 34 30
...

I would like to be able to update it in 2 different ways:

1- Partial update (WHERE attribute '14' LIKE '%11-29%') to target just specific records, or
2- A full database update in a single swing if it's possible

Thanks in advance, any help will be greatly appreciated.

Marco