Regular Expression Pattern maching class to Validate Alphanumeric String

Question

Hi
MY DB version is Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bit Production
I wanted to use the pattern maching classes given by oracle to check whether a given input string is alphanumeric or not.
Oracle 10g documentation says about the classes like [:digit:], [:alnum:] and many others.
http://www.dba-oracle.com/t_regular_expressions.htm
However these classes seems not to be working with my DB version.
Can someone tell me the DB version in which these classes works ?
Below is the code I am using to validate a input string.
SQL> CREATE OR REPLACE FUNCTION fn_is_alphanumeric
  2  (
  3     pi_value             IN       VARCHAR2
  4  )
  5  RETURN VARCHAR2
  6  IS
  7     lv_length   NUMBER;
  8  BEGIN
  9     lv_length := length(pi_value);
10     IF ( REGEXP_LIKE(pi_value,'[:alnum:]{'||lv_length||'}')) THEN
11        RETURN 'TRUE';
12     ELSE
13        RETURN 'FALSE';
14     END IF;
15  END fn_is_alphanumeric;
16  /
Function created.
SQL>
SQL>
SQL> SELECT fn_is_alphanumeric('abc123') alpha FROM DUAL;
ALPHA
FALSE
SQL>
SQL>
SQL> CREATE OR REPLACE FUNCTION fn_is_alphanumeric
  2  (
  3     pi_value             IN       VARCHAR2
  4  )
  5  RETURN VARCHAR2
  6  IS
  7     lv_length   NUMBER;
  8  BEGIN
  9     lv_length := length(pi_value);
10     IF ( REGEXP_LIKE(pi_value,'[A-z0-9]{'||lv_length||'}')) THEN
11        RETURN 'TRUE';
12     ELSE
13        RETURN 'FALSE';
14     END IF;
15  END fn_is_alphanumeric;
16  /
Function created.
SQL> SELECT fn_is_alphanumeric('abc123') alpha FROM DUAL;
ALPHA
TRUE

Answer 1

Character classes are working fine with regexp engine in your database version - simply change your function definition to:
CREATE OR REPLACE FUNCTION fn_is_alphanumeric
   pi_value             IN       VARCHAR2
RETURN VARCHAR2
IS
   lv_length   NUMBER;
BEGIN
   lv_length := length(pi_value);
   IF ( REGEXP_LIKE(pi_value,'[[:alnum:]]{'||lv_length||'}')) THEN
      RETURN 'TRUE';
   ELSE
      RETURN 'FALSE';
   END IF;
END fn_is_alphanumeric;
/(brackets should be doubled as compared with your original version).
You can use both , range-based and class-based expressions, but you have to keep in mind, that range-based are nls dependant as opposite to class-based.
SQL> alter session set nls_sort=binary;
Session altered.
SQL> with t as (
  2   select 'üäö123' s from dual
  3  )
  4  select
  5  case
  6  when regexp_like(s,'^[a-zA-Z0-9]+$') then 'Alphanumeric'
  7  else 'Not Alphanumeric'
  8  end range,
  9  case
10  when regexp_like(s,'^[[:alnum:]]+$') then 'Alphanumeric'
11  else 'Not Alphanumeric'
12  end class
13  from t
14  /
RANGE                CLASS
Not Alphanumeric     Alphanumeric
SQL>
SQL> alter session set nls_sort='GERMAN';
Session altered.
SQL> with t as (
  2   select 'üäö123' s from dual
  3  )
  4  select
  5  case
  6  when regexp_like(s,'^[a-zA-Z0-9]+$') then 'Alphanumeric'
  7  else 'Not Alphanumeric'
  8  end range,
  9  case
10  when regexp_like(s,'^[[:alnum:]]+$') then 'Alphanumeric'
11  else 'Not Alphanumeric'
12  end class
13  from t
14  /
RANGE                CLASS
Alphanumeric         AlphanumericBest regards
Maxim