Re: NULLS and User Input WAS Re: multimaster - Mailing list pgsql-general

From PFC
Subject Re: NULLS and User Input WAS Re: multimaster
Date
Msg-id op.ttdag4vycigqcu@apollo13
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In response to Re: NULLS and User Input WAS Re: multimaster  ("Ian Harding" <harding.ian@gmail.com>)
Responses Re: NULLS and User Input WAS Re: multimaster  (Andrew Sullivan <ajs@crankycanuck.ca>)
Re: NULLS and User Input WAS Re: multimaster  ("Ian Harding" <harding.ian@gmail.com>)
Re: NULLS and User Input WAS Re: multimaster  (Owen Hartnett <owen@clipboardinc.com>)
List pgsql-general
> Yeah, it is awful ;^)  However the existing system is equally awful
> because there is no way to enter NULL!

Consider this form :

First name :    Edgar
Middle name :    J.
Last name :    Hoover

Now, if someone has no middle name, like "John Smith", should we use NULL
or "" for the middle name ?
NULL usually means "unknown" or "not applicable", so I believe we have to
use the empty string here. It makes sense to be able to concatenate the
three parts of the name, without having to put COALESCE() everywhere.

Now consider this form :

City    :
State    :
Country    :

If the user doesn't live in the US, "State" makes no sense, so it should
be NULL, not the empty string. There is no unnamed state. Also, if the
user does not enter his city name, this does not mean he lives in a city
whose name is "". So NULL should be used, too.

It is very context-dependent.

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