NULL Values

I've problems retrieving a table where the key fields may contain NULL VALUES. The first problem is, that Oracle does not seem to distinguish between NULL VALUES, Empty Strings or even blank strings (which are trimmed to NULL). Isn't there any way to change this behaviour ? I want to retrieve the data in logical order, that means for me empty fields first. Because Oracle trims empty strings or strings of blanks to NULL and by default, returns NULLs last, I tried to use the NULLS FIRST clause in my query. But this is very slow, it seams Oracle will then no longer use the index if the query constraints via the index fields...
Isn't there any way to retrieve data with empty values first while reading using an index ? Received on Mon Jan 27 2003 - 20:07:30 CET