Merging 2 rows in a table - Mailing list pgsql-general

From Alexander Farber
Subject Merging 2 rows in a table
Date
Msg-id AANLkTi=wXTjAhJ5T22mW5Y_4ykMzv_xJ_Y5+JGr2Hy3s@mail.gmail.com
Whole thread Raw
Responses Re: Merging 2 rows in a table  (Pavel Stehule <pavel.stehule@gmail.com>)
List pgsql-general
Hello,

through some obscure error (probably on my side)
I have several thousand entries for Jan 1 and Jan 2
ending up in the ISO week 2011-52 instead of 2010-52
which breaks the bar chart at the top of my script
http://preferans.de/user.php?id=OK504891003571

# select * from pref_money where id='OK324712148886';
       id       | money |   yw
----------------+-------+---------
 OK324712148886 |   203 | 2010-46
 OK324712148886 |   219 | 2010-49
 OK324712148886 |   115 | 2010-51
 OK324712148886 |    63 | 2010-52
 OK324712148886 |    20 | 2011-01
 OK324712148886 |    10 | 2011-52

# \d pref_money
                        Table "public.pref_money"
 Column |         Type          |                Modifiers
--------+-----------------------+-----------------------------------------
 id     | character varying(32) |
 money  | integer               | not null
 yw     | character(7)          | default to_char(now(), 'YYYY-IW'::text)
Indexes:
    "pref_money_yw_index" btree (yw)
Foreign-key constraints:
    "pref_money_id_fkey" FOREIGN KEY (id) REFERENCES pref_users(id)

I would like to fix that problem by adding
2011-52 values of money (10 above) to the
2010-52 values of money (63 above, should become 73)
and then dropping all rows with the
wrong week number yw='2011-52'.

So I'm trying:

# update pref_money set money=money+
    (select money from pref_money where yw='2011-52')
    where yw='2010-52';
ERROR:  more than one row returned by a subquery used as an expression

ok, I probably need to specify the id for the subquery
in round brackets above - so I try again:

# update pref_money as m1 set money=money+
(select coalesce(money,0) from pref_money as m2
where m1.id=m2.id and m2.yw='2011-52')
where m1.yw='2010-52';
ERROR:  null value in column "money" violates not-null constraint

Can anybody please help me here?

Thank you
Alex

pgsql-general by date:

Previous
From: Thomas Schmidt
Date:
Subject: Re: Need advise for database structure for non linear data.
Next
From: Pavel Stehule
Date:
Subject: Re: Merging 2 rows in a table