REGEXP_INSTR « Regular Expressions Functions « Oracle PL/SQL Tutorial

18.2.1.Regexp_Instr returns the location (beginning) of a pattern in a given string
18.2.2.REGEXP_INSTR(x, pattern [, start [, occurrence [, return_option [, match_option]]]]) searches for pattern in x.
18.2.4.Parameters is a field that may be used to define how one wants the search to proceed:
18.2.5.Find the 's' and ignore case.
18.2.6.The simplest regular expression matches letters, letter for letter
18.2.7.SELECT REGEXP_INSTR('Two is bigger than One','One') where_it_is
18.2.8.Occurrence refers to the first, second, third, etc., occurrence of the pattern in S. The default is 1 (first).
18.2.9.Return-option returns the position of the start or end of the matched string.

18.2.10.The Return-option is set to 1 to indicate the end of the found pattern
18.2.11.Returns the position of the second occurrence that matches the regular expression s[[:alpha:]]{3} starting at position 1:
18.2.12.Returns the position of the second occurrence that matches the letter o starting at position 10 using REGEXP_INSTR()
18.2.13.Specify any series of letters and find matches, just like INSTR
18.2.14.regexp_instr(comments, '[^ ]+', 1, 9) > 0