Hello everyone.

I'm new to Oracle and have been at this for a while. I know I'm close but my data is just not sorting correctly. Can any experts chime in? THANKS!

ORDER BY TO_NUMBER(REGEXP_SUBSTR(a, '[0-9]+')), a

Outputs:
2B
3A
3B
4B
4B
4A
4B
4A
5
6

Need:
2B
3A
3B
4A
4A
4B
4B
4B
5
6

I've also tried the following with no success:
ORDER BY TO_NUMBER(REGEXP_SUBSTR(a, '^[[:digit:]]*')), a