Re: null foreign key column

From: Vernon Wu <vernonw(at)gatewaytech(dot)com>
To: pgsql-sql(at)postgresql(dot)org, Dmitry Tkach <dmitry(at)openratings(dot)com>
Subject: Re: null foreign key column
Date: 2003-02-12 22:35:07
Message-ID: FEY83IG42SQA7EB94TR71LGNMVUWSUO.3e4acc1b@kimiko
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12/02/2003 2:24:49 PM, Dmitry Tkach <dmitry(at)openratings(dot)com> wrote:

>You don't want it to be serial - just make it 'person_id in'

Any reasons?

>
>I hope, it helps...
>
>Dima
>
>Arunachalam Jaisankar wrote:
>> This is a multi-part message in MIME format.
>>
>> ------=_NextPart_000_0005_01C2D1EE.61998D70
>> Content-Type: text/plain;
>> charset="iso-8859-1"
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>>
>> Hi all,
>>
>> I would like to have a foreign key column in my table which allows null val=
>> ue also.
>> But the below create table sql command doesn't accept null value for person=
>> _id.
>> How to do in postgres?
>>
>> create table event
>> (
>> event_id serial not null,
>> event_description char(255) ,
>> person_id serial ,
>> primary key (event_id),
>> foreign key (person_id)
>> references person (person_id)
>> );
>>
>> regards
>> Jai
>> ------=_NextPart_000_0005_01C2D1EE.61998D70
>> Content-Type: text/html;
>> charset="iso-8859-1"
>> Content-Transfer-Encoding: quoted-printable
>>
>> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
>> <HTML><HEAD>
>> <META http-equiv=3DContent-Type content=3D"text/html; charset=3Diso-8859-1">
>> <META content=3D"MSHTML 6.00.2800.1106" name=3DGENERATOR>
>> <STYLE></STYLE>
>> </HEAD>
>> <BODY bgColor=3D#ffffff>
>> <DIV><FONT face=3DArial size=3D2>Hi all,</FONT></DIV>
>> <DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
>> <DIV><FONT face=3DArial size=3D2>I would like to have a foreign key column =
>> in my=20
>> table which allows null value also.</FONT></DIV>
>> <DIV><FONT face=3DArial size=3D2>But the below create table sql command doe=
>> sn't=20
>> accept null value for person_id.</FONT></DIV>
>> <DIV><FONT face=3DArial size=3D2>How to do in postgres?</FONT></DIV>
>> <DIV><FONT face=3DArial size=3D2></FONT><FONT face=3DArial size=3D2></FONT>=
>> &nbsp;</DIV>
>> <DIV><FONT face=3DArial size=3D2>create table event<BR>(<BR>&nbsp;&nbsp;&nb=
>> sp;=20
>> event_id&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&=
>> nbsp;&nbsp;&nbsp;=20
>> serial&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nb=
>> sp;&nbsp;&nbsp;&nbsp;=20
>> not null,<BR>&nbsp;&nbsp;&nbsp; event_description&nbsp;&nbsp;&nbsp;&nbsp;&n=
>> bsp;=20
>> char(255)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;=
>> &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;=20
>> ,<BR>&nbsp;&nbsp;&nbsp;=20
>> person_id&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;=
>> &nbsp;&nbsp;=20
>> serial&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nb=
>> sp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;=20
>> ,<BR>&nbsp;&nbsp;&nbsp; primary key (event_id),<BR>&nbsp;&nbsp;&nbsp; forei=
>> gn=20
>> key&nbsp; (person_id)<BR>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; references pe=
>> rson=20
>> (person_id)<BR>);</FONT></DIV>
>> <DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
>> <DIV><FONT face=3DArial size=3D2>regards</FONT></DIV>
>> <DIV><FONT face=3DArial size=3D2>Jai</FONT></DIV></BODY></HTML>
>>
>> ------=_NextPart_000_0005_01C2D1EE.61998D70--
>>
>
>
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