oracle (12c) regexp_substr to split filename and directoryname

Question

Using Oracle 12c, I'd like to split string containing full filename (including directory) to 2 strings : first one with the directory, second with the filename.

I already got filename but can't extract directory correctly :

select
   val,
   regexp_substr(val, '[^/]+/[^/]+', 1, 1) as dirname,
   regexp_substr(val, '[^/]+$', 1, 1) as filename
from (select '/a/b/c/d/e/f/file.ext' as val from dual) t

This gives:

dirname = a/b -- This is my purpose...
filename = file.ext -- This is correct !

I'd like to get dirname as

/a/b/c/d/e/f

including the 1st "/"

NB : I don't want to split into several lines (using connect by sentence). I need to get one row with 2 seperate strings...

Thanks...

Answer 1

We can try using REGEXP_SUBSTR and REGEXP_REPLACE as follows:

SELECT
    REGEXP_REPLACE(val, '/[^/]*$', '') AS path,
    REGEXP_SUBSTR(val, '[^/]+$') AS filename
FROM yourTable;

The basic strategy here is to remove the final slash and all proceeding it to obtain the directory path, and do the opposite to obtain the filename.

Answer 2

You don't need (slow) regular expressions and can just use SUBSTR and INSTR :

Oracle Setup :

CREATE TABLE test_data ( val ) AS
  SELECT '/a/b/c/d/e/f/file.ext' FROM DUAL;

Query :

SELECT SUBSTR( val, 1, INSTR( val, '/', -1 ) ) AS dir,
       SUBSTR( val, INSTR( val, '/', -1 ) + 1 ) AS filename
FROM   test_data;

Output :

\nDIR |  FILENAME \n:------------ |  :------- \n/a/b/c/d/e/f/ |  file.ext \n

db<>fiddle here