query to change column values

Hi ,

I have two columns in codes table where we have id(number) and code(varchar2)

I would like to change the if id =1 change it to A and 2 to B and rest change the id from 1..to 13
in this example I have total 15 and it changes

Code:

---

id        code
--          -----
1        99
2        105
3        78
4        66
5        54
6        42
7        30
8        141
9        147
10        153
11        159
12        165
13        171
14        177
15        183
       
----------------------------       
id        code
--          -----
A        99
B        105
1        78
2        66
3        54
4        42
5        30
6        141
7        147
8        153
9        159
10        165
11        171
12        177
13        183

---

I believe I can change 1 and 2 to a and b with decode but not sure how I
change the order to start from 1 again

any help is appreciated

thank you

First issue I can see "id" is of the number datatype, can't put a letter there.

assuming "id" is converted to the varchar2 datatype something like... id = (to_number(id) - 2) would do the trick for the non 1,2 values.

thank you