Count the Characters (SQL Puzzle 18)

Problem:
Given a string e.g 'gaurav goel' , return the individual character of the string along with its count in the whole string, with order kept intact.
The result should be:
g 2
a 2
u 1
r 1
v 1
NULL 1
0 1
e 1
l 1

Solution:
select ind,cn
from
(
select ind,cn,row_number() over (partition by ind order by ind) rownumber from
(
select
substr(given_input,rownum,1) ind,
rownum rn,
count(substr(given_input,rownum,1)) over (partition by substr(given_input,rownum,1)order by substr(given_input,rownum,1)) cn
from
(
select 'gaurav goel' given_input from all_objects
)
where
rownum<=length(given_input)
)
order by rn
)
where
rownumber=1