Update of two tables in a trigger

Hello world,

I am currently playing with postgres to learn a bit about it. I
created a database to contain information about manpages i printed.
(I am going to print a lot of them, and I don't want to do it
twice).

For some reason, I split the output in two tables, one to contain
the command and the section number, one for the number of pages and
sheets of paper, and the date I printed it.

I connected these two tables by creating a sequence, using the
nextval() as default value for a field in the first table and the
currval() as default in the second.

I also created a view (named v_manpages) that joins these two tables
together, based on the mentioned fields.

After failing to get it to work with rules, I am now trying to use
triggers and PL/pgSQL-functions for updating the view, but I am
experiencing rather strange things. The inserting of rows works
fine, but deleting...

Here's my problem:

manpage=> select * from v_manpages;
cmd       |section|pages|sheets|      when
----------+-------+-----+------+----------
procmailsc|5      |    5|     3|1999-05-24
sox       |1      |   11|     6|1999-05-24
chgrp     |1      |    1|     1|1999-05-24
procmailrc|5      |   14|     7|1999-05-24  

manpage=> insert into v_manpages values ('update','sql',1,1);
INSERT 20036 1   
manpage=> insert into v_manpages values ('test'1,2,1);
INSERT 20039 1

manpage=> select * from v_Manpages;
cmd       |section|pages|sheets|      when
----------+-------+-----+------+----------
procmailsc|5      |    5|     3|1999-05-24
sox       |1      |   11|     6|1999-05-24
chgrp     |1      |    1|     1|1999-05-24
procmailrc|5      |   14|     7|1999-05-24      
update    |sql    |    1|     1|1999-05-24
test      |1      |    2|     1|1999-05-24     

manpage=> delete from v_manpages where cmd = 'sox';
DELETE 1
manpage=> select * from v_Manpages;
cmd       |section|pages|sheets|      when
----------+-------+-----+------+----------
procmailsc|5      |    5|     3|1999-05-24
sox       |1      |   11|     6|1999-05-24
chgrp     |1      |    1|     1|1999-05-24
procmailrc|5      |   14|     7|1999-05-24     

Two are gone, sox is still present.

manpage=> delete from v_manpages where cmd = 'sox';
DELETE 0    

Now I can't delete anything more.

These are my tables, triggers and functions:

--------------

create table manpages (cmd text, section varchar(5), prnr int4
unique default nextval('seq_printnr'));

create table info (prnr int4 unique default currval('seq_printnr'),
pages int2, sheets int2, when date default current_date);

create view v_manpages as select cmd,section,pages,sheets,when from
manpages,info where manpages.prnr = info.prnr);

create function get_prnrfromcmd(text) returns int4 as '
select prnr from manpages where cmd = $1;
' language 'sql';

create function tp_v_manpages () returns opaque as '
declareprintnr int4;
beginif TG_OP = ''DELETE'' then    printnr = get_prnrfromcmd(OLD.cmd);    if printnr ISNULL then        return NULL;
endif;        delete from manpages where prnr = printnr;    delete from info where prnr = printnr;    return OLD;end
if;ifTG_OP = ''INSERT'' then    insert into manpages values (NEW.cmd,    NEW.section);
 
    printnr := get_prnrfromcmd(NEW.cmd);    if printnr ISNULL then        return NULL;    end if;    insert into info
values(printnr, NEW.pages,    NEW.sheets);    return NEW;end if;return NULL;
 
end;
' language 'plpgsql';

create trigger t_v_manpages
before insert or delete on v_manpages for each row
execute procedure tp_v_manpages();

------------

PostgreSQL version is 6.4.2.

What mistake did I make?

(If this mail is too long, or if there is information missing,
or if I am a complete fool, I'm very sorry. But please help me.)

-- 
Christian Ullrich

(I am a student, I live in Germany)