exception free to_number() subsitute?

Within a select which returns multiple rows, I need to do a conversion from a varchar2 field to a number. However, it is essential that the select will not break when the varchar2 happens to *not* contain a valid number. Basically, what I need is a to_number() substitute that will return a NULL when the string cannot be converted. Also, it needs to be *fast*.

Any suggestions? (short of writing a dedicated function that will parse the varchar2 field character by character)

TIA, -Allard Received on Thu Sep 11 1997 - 00:00:00 CDT