Oracle query to find all occurrences of a charcter in a string

Question

I have to write an Oracle query in toad to find all the occurrences of a character in a string. For example if I\'m searching for R in the string SSSRNNSR

Answer 1

This is a solution:

select
  pos
from
  (select
    substr('SSSRNNSRSSR', level, 1) as character,
    level as pos
  from
    dual
  connect by
    level <= length(t.text))
where
  character = 'R'

dual is a built in table that just returns a single row. Very convenient!

connect by lets you build recursive queries. This is often used to generate lists from tree-like data (parent/child relations). It allows you to more or less repeat the query in front of it. And you've got special fields, like level that allows you to check how deeply the recursion went.

In this case, I use it to split the string to characters and return a row for each character. Using level, I can repeat the query and get a character until the end of the string is reached.

Then it is just a matter of returning the pos for all rows containing the character 'R'