Re: Best practices for "Gender Column"

From: Matthias Hoys <>
Date: Tue, 7 Jul 2009 23:15:20 +0200
Message-ID: <4a53bb07$0$2850$>

"jose" <> wrote in message
> This days, I'm participating in the design of a new application for a
> Biotechnology company. I found the following:
> -In some applications they use for (Gender/sex column) NUMBER(1) and
> this could be Null because in some cases they don't know the Gender
> until they get the genotype, but in this applications the values are
> (1 = Male , 2 = Female and Null ), the problem with this solution is
> that in some cases when the people is reading the information always
> is asking 1 is for male o for female ?
> -In the new application I suggest to use VARCHAR2(1) for this column
> and this must be NOT NULL, and the possible values must be M=Male
> F=Female and U= Unknown. I think is better use a value against a Null
> because of the indexes, I mean in case we decided to index by this
> column the null values will never be indexed.
> I'm posting this to here any comments, thanks, Uriel.

Looks ok to me, you could then add a check constraint to the column (add CONSTRAINT gender_name CHECK (gender IN ('M','F','U')) and you could add a foreign key constraint to a "gender" table, with the varchar2(1) column as PK constraint and an additional column that describes the gender type. But what about hermaphrodite organisms? ;-)

Matthias Received on Tue Jul 07 2009 - 16:15:20 CDT

Original text of this message