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* Need help: Find dirty rows, Update, Delete SQL
@ 2006-02-18 17:41 ogjunk-pgjedan@yahoo.com
0 siblings, 1 reply; 3+ messages in thread
From: ogjunk-pgjedan@yahoo.com @ 2006-02-18 17:41 UTC (permalink / raw)
To: pgsql-sql
Hello,
I need a bit of help with some SQL.
I have two tables, call them Page and Bookmark.
Each row in Page can have many Bookmarks pointing to it, and
they are joined via a FK (Page.id = Bookmark.page_id).
Page has a 'url' column: Page.url, which has a unique index on it.
My Page.url column got a little dirty, and I need to clean it up,
and that's what I need help with.
Here is an example of dirtiness:
Page:
id=1 url = 'http://example.com/';
id=2 url = 'http://example.com/#'; -- dirty
id=3 url = 'http://example.com/#foo'; -- dirty
The last two rows are dirty. Normally I normalize URLs before
inserting them, but these got in, and now I need to clean them.
The problem is that rows in Bookmark table may point to dirty
rows in Page, so I can't just remove the dirty rows, and I can't
just update 'url' column in Page to 'http://example.com/';,
because that column is unique.
Is there some fancy SQL that I can use them to find the dirty
rows in page (... where url like '%#%') and then find rows in
Bookmark table that point to them, then point those rows to
good rows in Page (e.g. id=1 row above), and finally remove the
dirty rows from Page?
Any help would be greatly appreciated.
I'm using Pg 8.0.3
Thanks,
Otis
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: Need help: Find dirty rows, Update, Delete SQL
@ 2006-02-19 10:44 Janning Vygen <vygen@gmx.de>
parent: ogjunk-pgjedan@yahoo.com
0 siblings, 1 reply; 3+ messages in thread
From: Janning Vygen @ 2006-02-19 10:44 UTC (permalink / raw)
To: pgsql-sql; +Cc: ogjunk-pgjedan@yahoo.com
Am Samstag, 18. Februar 2006 18:41 schrieb ogjunk-pgjedan@yahoo.com:
> Hello,
>
> I need a bit of help with some SQL.
> I have two tables, call them Page and Bookmark.
> Each row in Page can have many Bookmarks pointing to it, and
> they are joined via a FK (Page.id = Bookmark.page_id).
>
> Page has a 'url' column: Page.url, which has a unique index on it.
>
> My Page.url column got a little dirty, and I need to clean it up,
> and that's what I need help with.
>
> Here is an example of dirtiness:
>
> Page:
>
> id=1 url = 'http://example.com/';
> id=2 url = 'http://example.com/#'; -- dirty
> id=3 url = 'http://example.com/#foo'; -- dirty
>
> The last two rows are dirty. Normally I normalize URLs before
> inserting them, but these got in, and now I need to clean them.
>
> The problem is that rows in Bookmark table may point to dirty
> rows in Page, so I can't just remove the dirty rows, and I can't
> just update 'url' column in Page to 'http://example.com/';,
> because that column is unique.
>
> Is there some fancy SQL that I can use them to find the dirty
> rows in page (... where url like '%#%') and then find rows in
> Bookmark table that point to them, then point those rows to
> good rows in Page (e.g. id=1 row above), and finally remove the
> dirty rows from Page?
try this. But please check if it really does its job. I just wrote it down in
a minute or two. There will be an easier way or nicer written SQL but a sit
is just a one time operation you shoudn't care too much. One more hint: you
should add a CHECK clause to your page_url like "page_url text NOT NULL
UNIQUE CHECK (page_url !~ '#')"
here is my test code
CREATE TABLE pages (
page_id SERIAL PRIMARY KEY,
page_url text NOT NULL UNIQUE
);
CREATE TABLE bookmarks (
bm_id SERIAL PRIMARY KEY,
bm_text text not null,
page_id int4 NOT NULL REFERENCES pages (page_id)
);
INSERT INTO pages (page_url) VALUES ('http://example.com/';);
INSERT INTO pages (page_url) VALUES ('http://example.com/#';);
INSERT INTO pages (page_url) VALUES ('http://example.com/#foo';);
INSERT INTO pages (page_url) VALUES ('http://example2.com/#foo';);
INSERT INTO pages (page_url) VALUES ('http://example3.com/#foobar';);
insert into bookmarks (bm_text, page_id) values ('test1', 1);
insert into bookmarks (bm_text, page_id) values ('test2', 1);
insert into bookmarks (bm_text, page_id) values ('test3', 2);
insert into bookmarks (bm_text, page_id) values ('test4', 2);
insert into bookmarks (bm_text, page_id) values ('test5', 3);
insert into bookmarks (bm_text, page_id) values ('test6', 3);
insert into bookmarks (bm_text, page_id) values ('test7', 4);
BEGIN;
UPDATE bookmarks set page_id = pages2.page_id
FROM
pages AS pages1,
pages AS pages2
WHERE
pages1.page_id = bookmarks.page_id
AND pages2.page_url = split_part(pages1.page_url, '#', 1)
;
DELETE FROM pages WHERE page_id IN (
SELECT
pages1.page_id
FROM
pages AS pages1
JOIN pages AS pages2 ON (
pages1.page_id != pages2.page_id
AND pages2.page_url = split_part(pages1.page_url, '#', 1)
)
WHERE position('#' in pages1.page_url) > 0
AND pages1.page_id NOT IN (SELECT page_id FROM bookmarks)
);
;
UPDATE pages SET page_url = split_part(page_url, '#', 1)
WHERE position('#' in pages.page_url) > 0
;
select * from bookmarks;
select * from pages;
COMMIT;
kind regards,
janning
^ permalink raw reply [nested|flat] 3+ messages in thread
* Re: Need help: Find dirty rows, Update, Delete SQL
@ 2006-02-20 11:24 Patrick JACQUOT <patrick.jacquot@anpe.fr>
parent: Janning Vygen <vygen@gmx.de>
0 siblings, 0 replies; 3+ messages in thread
From: Patrick JACQUOT @ 2006-02-20 11:24 UTC (permalink / raw)
To: Janning Vygen <vygen@gmx.de>; +Cc: pgsql-sql; ogjunk-pgjedan@yahoo.com
Janning Vygen wrote:
>Am Samstag, 18. Februar 2006 18:41 schrieb ogjunk-pgjedan@yahoo.com:
>
>
>>Hello,
>>
>>I need a bit of help with some SQL.
>>I have two tables, call them Page and Bookmark.
>>Each row in Page can have many Bookmarks pointing to it, and
>>they are joined via a FK (Page.id = Bookmark.page_id).
>>
>>Page has a 'url' column: Page.url, which has a unique index on it.
>>
>>My Page.url column got a little dirty, and I need to clean it up,
>>and that's what I need help with.
>>
>>Here is an example of dirtiness:
>>
>>Page:
>>
>>id=1 url = 'http://example.com/';
>>id=2 url = 'http://example.com/#'; -- dirty
>>id=3 url = 'http://example.com/#foo'; -- dirty
>>
>>The last two rows are dirty. Normally I normalize URLs before
>>inserting them, but these got in, and now I need to clean them.
>>
>>The problem is that rows in Bookmark table may point to dirty
>>rows in Page, so I can't just remove the dirty rows, and I can't
>>just update 'url' column in Page to 'http://example.com/';,
>>because that column is unique.
>>
>>Is there some fancy SQL that I can use them to find the dirty
>>rows in page (... where url like '%#%') and then find rows in
>>Bookmark table that point to them, then point those rows to
>>good rows in Page (e.g. id=1 row above), and finally remove the
>>dirty rows from Page?
>>
>>
>
>try this. But please check if it really does its job. I just wrote it down in
>a minute or two. There will be an easier way or nicer written SQL but a sit
>is just a one time operation you shoudn't care too much. One more hint: you
>should add a CHECK clause to your page_url like "page_url text NOT NULL
>UNIQUE CHECK (page_url !~ '#')"
>
>here is my test code
>
>CREATE TABLE pages (
> page_id SERIAL PRIMARY KEY,
> page_url text NOT NULL UNIQUE
>);
>
>CREATE TABLE bookmarks (
> bm_id SERIAL PRIMARY KEY,
> bm_text text not null,
> page_id int4 NOT NULL REFERENCES pages (page_id)
>);
>
>INSERT INTO pages (page_url) VALUES ('http://example.com/';);
>INSERT INTO pages (page_url) VALUES ('http://example.com/#';);
>INSERT INTO pages (page_url) VALUES ('http://example.com/#foo';);
>INSERT INTO pages (page_url) VALUES ('http://example2.com/#foo';);
>INSERT INTO pages (page_url) VALUES ('http://example3.com/#foobar';);
>
>insert into bookmarks (bm_text, page_id) values ('test1', 1);
>insert into bookmarks (bm_text, page_id) values ('test2', 1);
>insert into bookmarks (bm_text, page_id) values ('test3', 2);
>insert into bookmarks (bm_text, page_id) values ('test4', 2);
>insert into bookmarks (bm_text, page_id) values ('test5', 3);
>insert into bookmarks (bm_text, page_id) values ('test6', 3);
>insert into bookmarks (bm_text, page_id) values ('test7', 4);
>
>BEGIN;
>UPDATE bookmarks set page_id = pages2.page_id
>FROM
> pages AS pages1,
> pages AS pages2
>WHERE
> pages1.page_id = bookmarks.page_id
> AND pages2.page_url = split_part(pages1.page_url, '#', 1)
>;
>
>DELETE FROM pages WHERE page_id IN (
> SELECT
> pages1.page_id
> FROM
> pages AS pages1
> JOIN pages AS pages2 ON (
> pages1.page_id != pages2.page_id
> AND pages2.page_url = split_part(pages1.page_url, '#', 1)
> )
> WHERE position('#' in pages1.page_url) > 0
> AND pages1.page_id NOT IN (SELECT page_id FROM bookmarks)
>);
>;
>
>UPDATE pages SET page_url = split_part(page_url, '#', 1)
>WHERE position('#' in pages.page_url) > 0
>;
>select * from bookmarks;
>select * from pages;
>COMMIT;
>
>
>kind regards,
>janning
>
>---------------------------(end of broadcast)---------------------------
>TIP 3: Have you checked our extensive FAQ?
>
> http://www.postgresql.org/docs/faq
>
>
>
why do you consider as dirty perfectly honest URLs as
http://example.com#foo ?
Such a construct points to a specific part (foo) of a specific document
(http://example.com)
^ permalink raw reply [nested|flat] 3+ messages in thread
end of thread, other threads:[~2006-02-20 11:24 UTC | newest]
Thread overview: 3+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2006-02-18 17:41 Need help: Find dirty rows, Update, Delete SQL ogjunk-pgjedan@yahoo.com
2006-02-19 10:44 ` Janning Vygen <vygen@gmx.de>
2006-02-20 11:24 ` Patrick JACQUOT <patrick.jacquot@anpe.fr>
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