Need help in finding the number of occurrences of a pattern.

Question

Hi All,
I need help in finding the number of occurrences of a pattern in a table's column's data.
Consider sample data - one row's column from a table:
"S-S-S-A-S-S-P-S-S-B-S-A-P-S-S-C"
My requirement is:
I should get the count of S's which are immediately preceded by A or P.
for the above data i should get count as 3+2+1=6 (S-S-S-A, S-S-P, S-A)
The pattern data is stored as VARCHAR2 type.
Thanks in advance,
Girish G
Edited by: Girish G on Jul 21, 2011 11:22 PM

Answer 1

I am sure there exists a better way then this one:
SQL> with dt as
  2  (select 'S-S-S-A-S-S-P-S-S-B-S-A-P-S-S-C' str from dual)
  3  SELECT SUM(Regexp_count(Regexp_substr(str, '(S\-?)+(A|P)+', 1,
  4                                     Regexp_count(str, '(S\-?)+(A|P)+') - (
  5                                                  LEVEL - 1 )), 'S')) len
  6  FROM   dt
  7  CONNECT BY LEVEL <= Regexp_count(str, '(S\-?)+(A|P)+')
  8  /
       LEN
         6