Oracle trim whitespace on the inside of a string

Question

I am storing phone numbers as VARCHAR2 in my system to allow for users to input '+' characters infront of their phone number if they so choose.

My regexp allows for this perfectly, but when storing the number in the database I want to strip out all whitespace the user may enter.

My regexp allows for the following formats

+4470123456789
+447 0123456789
+447 01234 56789
01234567890
01234 567890
01234 567 890

I know I could resolve my issue by not letting users put any whitespace in their numbers, but I know from personal experience just how frustrating it is to have a validation error due to some silly formatting on the client side. I have tried using the TRIM function on my INSERT/UPDATE trigger but I have realised that is limited to only front and trailing whitespace, is there any other function in Oracle I could use that would remove internal whitespace? Or do I need to write my own function to do this?

Any pointers would be greatly appreciated.

Answer 1

You want to try replace (telno, ' ', '').

Answer 2

a better approach is to use a regular expression to remove all spaces within a string

SQL> with t as (
    select 'AAA    BBB CCC' col from dual union
    select 'DDDD EEE     F' col from dual 
    )
    --
    -- actual query:
    --
    select regexp_replace(col, '[[:space:]]+', chr(32)) col
    from   t;

COL

AAA BBB CCC DDDD EEE F