Re: [SQL] null foreign key column

Dmitry Tkach Wed, 12 Feb 2003 12:51:39 -0800

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

I hope, it helps...

Dima

Arunachalam Jaisankar wrote:

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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
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<!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">
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<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>

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Re: [SQL] null foreign key column

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