Insert data into a field whose field name is = date('j')

[harman]

Hi guys, I dont know if this is even possible but see if any one can help me with this. I have a table as follows:

| ID | p_id | 1 | 2 |...

Now suppose today is the 2nd of this month, i want to insert some data in to the field "2", similarly if today is the 20th i want to insert some data in to the field "20".

I dont want to do this:
UPDATE tablename SET 1='value'... since ill have to write 31 different update satements and then use the one appropriate for that day.