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* simple addition of constraints problem
@ 2004-06-08 21:51 Michelle Murrain <tech@murrain.net>
0 siblings, 2 replies; 3+ messages in thread
From: Michelle Murrain @ 2004-06-08 21:51 UTC (permalink / raw)
To: pgsql-sql
Hi All,
I'm trying to do something which seems really simple to me. (Postgres 7.3.4)
I've got this table:
charter_dev2=# \d rcourseinfo
Table "public.rcourseinfo"
Column | Type | Modifiers
-------------+-----------------------+---------------------------------------------------
courseid | integer | not null default
nextval('rcourseinfo_seq'::text)
coursename | character varying(50) |
dept | character varying(30) |
number | character varying(4) |
section | character varying(2) |
trimester | character varying(5) |
schoolyear | character varying(8) |
facultyid | integer |
description | text |
credits | real |
Indexes: rcourseinfo_pkey primary key btree (courseid),
rcourseinfo_number_index btree (number)
With a primary key called 'courseid'.
I've got a second table:
charter_dev2=# \d coursesevaluations
Table "public.coursesevaluations"
Column | Type | Modifiers
-----------------------+---------+----------------------------------------------------------
courseid | integer |
evalid | integer |
coursesevaluations_id | integer | not null default
nextval('coursesevaluations_seq'::text)
Indexes: coursesevaluations_pkey primary key btree (coursesevaluations_id),
coursesevaluations_evalid_index btree (evalid)
I'd like to make 'courseid' in this second table a foreign key,
referencing 'courseid' in the first table. So I did this command:
charter_dev2=# ALTER TABLE coursesevaluations ADD CONSTRAINT rc_ce
FOREIGN KEY (courseid) REFERENCES rcourseinfo (courseid);
And I get this result:
NOTICE: ALTER TABLE will create implicit trigger(s) for FOREIGN KEY check(s)
ERROR: rc_ce referential integrity violation - key referenced from
coursesevaluations not found in rcourseinfo
This doesn't make any sense to me - the fields are named the same,
and are the same data type. I've pored over the docs, to no avail.
I'm sure I'm missing something really elementary, but it's escaping
me.
I did try the following (because the error said "key referenced"):
ALTER TABLE coursesevaluations ADD CONSTRAINT rc_ce FOREIGN KEY
(courseid) REFERENCES rcourseinfo (rcourseinfo_pkey);
I got the error :
ERROR: ALTER TABLE: column "rcourseinfo_pkey" referenced in foreign
key constraint does not exist
!!
Thanks for any advice.
--
.Michelle
--------------------------
Michelle Murrain
mmurrain at dbdes dot com
413-222-6350 ph
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952-674-7253 fax <--- new
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"Work like you don't need the money. Love like you've never been
hurt. Dance like nobody's watching." - Satchel Paige
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: [SQL] simple addition of constraints problem
@ 2004-06-08 22:55 Richard Poole <rp@guests.deus.net>
parent: Michelle Murrain <tech@murrain.net>
1 sibling, 0 replies; 3+ messages in thread
From: Richard Poole @ 2004-06-08 22:55 UTC (permalink / raw)
To: pgsql-general@postgresql.org
On Tue, Jun 08, 2004 at 05:51:22PM -0400, Michelle Murrain wrote:
> I'd like to make 'courseid' in this second table a foreign key,
> referencing 'courseid' in the first table. So I did this command:
>
> charter_dev2=# ALTER TABLE coursesevaluations ADD CONSTRAINT rc_ce
> FOREIGN KEY (courseid) REFERENCES rcourseinfo (courseid);
>
> And I get this result:
>
> NOTICE: ALTER TABLE will create implicit trigger(s) for FOREIGN KEY
> check(s)
> ERROR: rc_ce referential integrity violation - key referenced from
> coursesevaluations not found in rcourseinfo
What this is telling you is not that there is any problem with your
formulation of the constraint (which as far as I can tell is what you
want), but that the existing data in the tables violates the constraint
you're trying to impose. If you do something like
SELECT rcoursesevaluations.courseid
FROM rcoursesevalutations NATURAL LEFT JOIN rcourseinfo
WHERE rcourseinfo.courseid IS NULL
you should see which courseids appear in rcoursesevaluations but not in
rcourseinfo.
Richard
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: simple addition of constraints problem
@ 2004-06-08 23:18 Stephan Szabo <sszabo@megazone.bigpanda.com>
parent: Michelle Murrain <tech@murrain.net>
1 sibling, 0 replies; 3+ messages in thread
From: Stephan Szabo @ 2004-06-08 23:18 UTC (permalink / raw)
To: Michelle Murrain <tech@murrain.net>; +Cc: pgsql-sql
On Tue, 8 Jun 2004, Michelle Murrain wrote:
> I'm trying to do something which seems really simple to me. (Postgres 7.3.4)
>
> I've got this table:
>
> charter_dev2=# \d rcourseinfo
> Table "public.rcourseinfo"
> Column | Type | Modifiers
> -------------+-----------------------+---------------------------------------------------
> courseid | integer | not null default
> nextval('rcourseinfo_seq'::text)
> coursename | character varying(50) |
> dept | character varying(30) |
> number | character varying(4) |
> section | character varying(2) |
> trimester | character varying(5) |
> schoolyear | character varying(8) |
> facultyid | integer |
> description | text |
> credits | real |
> Indexes: rcourseinfo_pkey primary key btree (courseid),
> rcourseinfo_number_index btree (number)
>
> With a primary key called 'courseid'.
>
> I've got a second table:
>
> charter_dev2=# \d coursesevaluations
> Table "public.coursesevaluations"
> Column | Type | Modifiers
> -----------------------+---------+----------------------------------------------------------
> courseid | integer |
> evalid | integer |
> coursesevaluations_id | integer | not null default
> nextval('coursesevaluations_seq'::text)
> Indexes: coursesevaluations_pkey primary key btree (coursesevaluations_id),
> coursesevaluations_evalid_index btree (evalid)
>
>
> I'd like to make 'courseid' in this second table a foreign key,
> referencing 'courseid' in the first table. So I did this command:
>
> charter_dev2=# ALTER TABLE coursesevaluations ADD CONSTRAINT rc_ce
> FOREIGN KEY (courseid) REFERENCES rcourseinfo (courseid);
>
> And I get this result:
>
> NOTICE: ALTER TABLE will create implicit trigger(s) for FOREIGN KEY check(s)
> ERROR: rc_ce referential integrity violation - key referenced from
> coursesevaluations not found in rcourseinfo
>
> This doesn't make any sense to me - the fields are named the same,
> and are the same data type. I've pored over the docs, to no avail.
> I'm sure I'm missing something really elementary, but it's escaping
> me.
That's the message for the constraint violation. It looks like perhaps
the data doesn't meet the constraint (in 7.4 it would have shown you
values, for 7.3 you'll have to look yourself).
^ permalink raw reply [nested|flat] 3+ messages in thread
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2004-06-08 21:51 simple addition of constraints problem Michelle Murrain <tech@murrain.net>
2004-06-08 22:55 ` Richard Poole <rp@guests.deus.net>
2004-06-08 23:18 ` Stephan Szabo <sszabo@megazone.bigpanda.com>
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