How to rank() by a particluar value

Question

HI,
i am trying to rank a column on the condition that a particular value exists
select * from t
id   col2                
1    1                        
2    17                       
3    1                          
4    1                          
5    11                          
6    1                          
i want to rank the values of col2 order by ID where col2 = 1.
If col2 value is not 1 then rank column should show 0
in other words, rank would show the progressive occurance of value = 1 in col2 order by ID column
the desired output
id   col2        rank         
1    1                 1        
2    17               0         
3    1                 2         
4    1                 3         
5    11               0         
6    1                 4          pls tell how to achieve this
create table t
(id number,
col2 number)
insert into t values ( 1, 1)
insert into t values (2, 17)
insert into t values (3 , 1)
insert into t values (4 , 1)
insert into t values (5 , 11)
insert into t values (6 , 1)

Answer 1

Todd Barry ,
thankyou so much for such a short query, worked perfectly
one more thing, if i also want to include 17 in my condition so that the the ranking should be done if the values of col2 order by ID are 1 or 17
If col2 value is not 1 or 17 then rank column should show 0
In other words, rank would show the progressive occurance of value = 1 or value = 17 in col2 order by ID
i have tried this
select t.*,
  decode(col2, 1, rank() over (order by decode(col2, 1, 0, null), id),
               17, rank() over (order by decode(col2, 17, 0, null), id), 0)  rank
     from t
    order by id
and this gives me this. its wrong, it starts ranking again from start when col2  =17
        ID       COL2       RANK
         1          1          1
         2         17         1
         3          1          2
         4          1          3
         5         11         0
         6          1          4
so my
desired output is
[pre]
        ID       COL2       RANK
         1          1          1
         2         17         2
         3          1          3
         4          1          4
         5         11         0
         6          1          5
[pre]
i would be most grateful if query is short like ur first one
regards,
asim