On Aug 23, 3:13 pm, "Martin T." <0xCDCDC..._at_gmx.at> wrote:
> William Robertson wrote:
> > On Aug 22, 7:22 pm, "Paul Linehan" <plinehan__A_at_T__yahoo__D.OT__COM>
> > wrote:
> >> Mark D Powell wrote:
> >>> I have always had difficulty with the concept that an empty string
> >>> should not be considered a NULL value to begin with. What does an
> >>> empty string hold?
> >> Take an ex-girlfriend of mine, she had a child in the States
> >> and *_specifically_* didn't give her (the child) a middle name.
>
> >> So, Middle_Initial is blank '' - and not NULL, since it is a
> >> known quantity - as Donald Rumsfeld might say, a "known unknown".
>
> >> NULLs are unknown unknowns. Despite Mr. Rumsfeld's verbal
> >> gymnastics, there is no such thing as an unknown known.
>
> >> You concatenate blank with a string, and you simply get the string
> >> back - do the same with NULL and you get NULL.
>
> >> I'd say NULLs are readily distinguishable from blank strings.
>
> >> Paul...
>
> > (...)
>
> > Oracle treats nulls as empty strings when concatenating, often leading
> > to cries of inconsistency in this sort of debate, but it is the
> > overwhelmingly more useful behaviour.
>
> Yeah. And Length('') == NULL which is bloody awful.
> Imho, Oracle just messed up on varchar2 and NULL. (from a practical, not
> a philosophical point of view)
>
> br,
> Martin
Well as theses debates always show it can be debated endlessly, but
surely a length of 0 is incorrect for an unknown value; and even in
the case of specifically-no-middle-name guy, if we are not including
it in a count (how many names does he have?) surely it would be
inconsistent to give it a length (what's the average length of his
names?)
Received on Fri Aug 24 2007 - 03:21:43 CDT
