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Message-Id: <26EC0BB6-61A9-4DBE-BEB0-7043F44A5A9D@yahoo.com>
Cc: "PostgreSQL \(SQL\)" <pgsql-sql@postgresql.org>
From: David Johnston <polobo@yahoo.com>
Subject: Re: Unable To Alter Data Type
Date: Wed, 11 Jan 2012 20:21:25 -0500
To: Carlos Mennens <carlos.mennens@gmail.com>

On Jan 11, 2012, at 19:30, Carlos Mennens <carlos.mennens@gmail.com> wrote:

> On Wed, Jan 11, 2012 at 7:13 PM, David Johnston <polobo@yahoo.com> wrote:
>> However, I will say again, you DO NOT WANT TO ACTUALLY DO THIS!
>>=20
>> The specific issue is that some US Postal Code begin with a zero ( 0 ) an=
d
>> so whenever you want to the zip_code value you need to pad leading zeros i=
f
>> the length is less than 5.  Now consider that a full zip_code can be in 5=
+4
>> format with an embedded hyphen and you no longer can even store it as
>> numeric.  If you deal with Canada (and maybe Mexico) at all then spaces a=
nd
>> letters become acceptable characters within the zip_code.
>=20
> David - Thank you for that great info / explanation. Very informative
> and helpful. I was not required to make this change but rather just
> goofing off attempting to learn SQL as I'm rather terrible at it. Can
> you tell me if there's an organized cheat sheet or something
> documented in regards to data types commonly used for commonly used
> field association? I think that's great for people who can't look at
> the documentation and clearly understand specific definitions or
> assumed categorization based on the type definition.

If you can perform reasonable arithmetic on the field value you encode it as=
 a number otherwise  you should use text; even if the only possibly valid va=
lues are numbers.

David J.