[thelist] Re: Hn tags

[rudy]

> Thoughts on forward compatibility? Any risks?

heh

not in my lifetime   ;o)

<tip type="sql">
  "A bad encoding scheme lacks codes for missing, unknown, not applicable,
or miscellaneous values.  The classic story is the man who bought a
prestige auto tag reading "NONE" and got thousands of traffic tickets as a
result. The police had no special provision for a missing tag on the
tickets, so when a car had no tag, they wrote "none" in the field for the
tag number. The database simply matched his name and address to every
unpaid missing-tag ticket on file at the time.
  "Before you say that the NULL in SQL is a quick solution to this problem,
think about how NULL is ignored in many SQL functions. The SQL query SELECT
tagno, SUM(fine) FROM tickets GROUP BY tagno will give the total fines on
each car. But it also puts all the missing tags into one group (i.e. one
car) although we want to see each one as a separate case, since it is very
unlikely that there is only one untagged car in all of California."
         - Joe Celko
              SQL for Smarties
</tip>

rudy
http://rudy.ca/
"you don't care for me
i don't care about that
you've got a new fool
hah, i like it like that
i have only one itchin desire --
lemme stand next to your fire"