How to get a subset of text from a varchar2 field

Question

Hello.  I am trying to select a subset of text from a varchar2 field.  This is login information from dba_audit_trail view.  Here's an example of the field (comment_text from dba_audit_trail):
Authenticated by: DIRECTORY PASSWORD;EXTERNAL NAME: cn=orcladmin,cn=Users,dc=idacorp,dc=local; Client address: (ADDRESS=(PROTOCOL=tcp)(HOST=555.555.555.555)(PORT=99999))
I am trying to just select the "orcladmin" text - i.e. everything after the first "=" up to the first ","
I can get everything after the first "=" with this:
select substr(comment_text, instr(comment_text, '=') + 1) from dba_audit_trail
... but I don't know how to stop at the first ","
Any help would be greatly appreciated.
Thanks!
Message was edited by: DRC

Answer 1

Hi,
Here's one way to do it:
WITH got_pos    AS
    SELECT  comment_text    -- and whatever other columns you need
    ,       INSTR (cooment_text, '=')   AS equal_pos
    ,       INSTR (cooment_text, ',')   AS comma_pos
    FROM    dba_auit_trail
    WHERE   ...             -- any filtering goes here
SELECT  SUBSTR ( comment_text
               , equal_pos + 1
               , comma_pos - (equal_pos + 1)
               )   AS first_cn
FROM    got_pos
You could do it without a sub-query; you'd just have to do the exact same INSTR 2 times, where I used equal_pos 2 times.
You could also get the results you want using regular expressions, such as:
SELECT  REGEXP_SUBSTR ( comment_text
                      , '=([^,]*),'
                      , 1
                      , 1
                      , NULL
                      , 1
                      )      AS first_cn
FROM    dba_audit_trail
Although this uses less code, it's slower than using INSTR and SUBSTR .