Character count in a String

Question

Write a SQL statement to show how many R's in the 'Ram Ratan Sarkar' string.

Answer 1

1. remove all characters from a string except 'x' using regexp_relplace (example: 'ab,xc dx' --> 'xx')
2. remove all characters from a string except 'x' and 'y' using regexp_relplace (example: 'aby,xc dx' --> 'yxx')
SQL>
SQL>
with t as (
  select 'ab,xc dx' as str from dual union all
  select 'an x and few more xxx''s here' from dual union all
  select 'xyz-xyz-xyz-xyz-xyz' from dual)
select
  str,
  regexp_replace(str,'[^x]') as mod_str
from t;
STR                          MOD_STR
ab,xc dx                     xx
an x and few more xxx's here xxxx
xyz-xyz-xyz-xyz-xyz          xxxxx
SQL>
SQL>
with t as (
  select 'aby,xc dx' as str from dual union all
  select 'an x and a y and few more yyyy''s and xxx''s here' from dual union all
  select 'xyz-xyz-xyz-xyz-xyz' from dual)
select
  str,
  regexp_replace(str,'[^xy]') as mod_str
from t;
STR                                             MOD_STR
aby,xc dx                                       yxx
an x and a y and few more yyyy's and xxx's here xyyyyyxxx
xyz-xyz-xyz-xyz-xyz                             xyxyxyxyxy
SQL>
SQL>pratz