> > oh and what is the best datatype to use for a 10 digit phone number?.
-snip-
> Secondly, for a phone number, ask yourself how you're going to treat it.
> Are you going to do a sum() across the numbers? Or maybe multiply them
> together?
>
> If yes, then you should store them as some kind of numeric, int, or as a
> float.
>
> If, however, the numbers are not going to be used for math but for
> identification, then it is likely that a text / varchar type would be a
> better choice.
Don't use int:
create table foo (ph int);
insert into foo values (5105551212);
ERROR: dtoi4: integer out of range
Use char(10).
Better yet, "properly" normalize phone numbers into area-code (char(3)),
prefix (char(3)) and number (char(4)) fields. This way you can error-check
your phones against the area-code table, determine approximate geographical
areas/time-zones, flag dangerous numbers (very high cost off-shore versions
of 900/976 numbers that look like ordinary phone numbers), etc.
If you really want to you can even include a prefix table to do the same
thing at the exchange level using NANPA data.
Even if you don't use a prefix table, updating your table when area-codes
split will be easier if the ac and prefix are in their own fields.
It may be overkill for your app but for a variety of reasons is a requirement
for ours.
Cheers,
Steve