Re: update with subselect (long)

From: Stephan Szabo <sszabo(at)megazone(dot)bigpanda(dot)com>
To: "Leif B(dot) Kristensen" <leif(at)solumslekt(dot)org>
Cc: pgsql-sql(at)postgresql(dot)org
Subject: Re: update with subselect (long)
Date: 2005-03-17 14:01:27
Message-ID: 20050317055420.S10944@megazone.bigpanda.com
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On Thu, 17 Mar 2005, Leif B. Kristensen wrote:

> CREATE TABLE name_part_types ( -- a key/label pair
> name_part_type_id INTEGER PRIMARY KEY,
> name_part_type VARCHAR(50)
> );
>
>
> CREATE TABLE names ( -- one person can have multiple names
> name_id INTEGER PRIMARY KEY,
> person_id INTEGER REFERENCES persons,
> is_primary BOOLEAN NOT NULL -- but one must be primary
> );
>
>
> CREATE TABLE name_parts ( -- a name has multiple name-parts
> name_part_id INTEGER PRIMARY KEY,
> name_id INTEGER REFERENCES names,
> name_part_type INTEGER REFERENCES name_part_types,
> name_sequence INTEGER NOT NULL, -- internal sort order of name part
> name_part VARCHAR(100)
> );
>
> My name_part_types table presently looks like this:
>
> slekta=> select * from name_part_types;
> name_part_type_id | name_part_type
> -------------------+----------------
> 1 | prefix
> 2 | given
> 3 | surname
> 4 | suffix
> 5 | patronym
> 6 | toponym
> (6 rows)
>
> My current genealogy program, The Master Genealogist (TMG), stores names
> in the conventional pigeon-hole way, within the fields Prefix / Given /
> Surname / Suffix. This form is quite awkward regarding old Norwegian
> naming practice, and I have been using the Surname field mainly for
> recording patronyms, and the Suffix field for toponyms (ie. "farm
> names"). I've written a FoxPro to SQL conversion script (using Perl and
> the XBase module) to dump the data from the TMG database. A typical
> name_parts set may look like this:
>
> slekta=> select * from name_parts where name_id = 1652;
> name_part_id | name_id | name_part_type | name_sequence | name_part
> --------------+---------+----------------+---------------+--------------
> 3643 | 1652 | 2 | 0 | Christen
> 3644 | 1652 | 5 | 1 | Jonsen
> 3645 | 1652 | 6 | 2 | Stavdal
> (3 rows)
>
> Now I'm starting to approach my point. The values (2,3,4) in the
> name_part_type column should be changed to (2,5,6). As the Suffix field
> in the overwhelming majority of instances is used only if the name is
> on the Given / Patronym / Toponym form, I figure that it should be easy
> to change the name_part_type here. Initially, I ran this update:
>
> slekta=> update name_parts set name_part_type=6 where name_part_type=3;
>
> So far, so good. But how do I change the name_part_type from 3 to 5 for
> the names with the same name_id that were altered by the previous
> command? This is my latest try:
>
> slekta=> begin work;
> BEGIN
> slekta=> update name_parts set name_part_type=5
> slekta-> from (select name_id where name_part_type=6) as gpt_type
> slekta-> where name_id=gpt_type and name_part_type=3;
> ERROR: subquery in FROM may not refer to other relations of same query
> level

The above needs some work. The below should be acceptable to the system.

update name_parts set name_part_type=5 from (select name_id from
name_parts where name_part_type=6) as gpt_type where
name_parts.name_id=gpt_type.name_id and name_part_type=3;

I'm a bit worried about blindly changing the type for anything that has a
name_part_type=6 record, but given your usage that might be okay.

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