On 11/05/2016 11:56 AM, Edson Richter wrote:
-----Mensagem original-----
De: Adrian Klaver [mailto:adrian.klaver@xxxxxxxxxxx]
Enviada em: sábado, 5 de novembro de 2016 15:13
Para: Edson Richter <edsonrichter@xxxxxxxxxxx>; pgsql-
general@xxxxxxxxxxxxxx
Assunto: Re: Trouble with regexp_matches
On 11/05/2016 10:01 AM, Edson Richter wrote:
Dear list,
Version string PostgreSQL 9.4.10 on x86_64-unknown-linux-gnu,
compiled by gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-4), 64-bit
I’m running the query below, and it is limiting results as if
“regexp_matches” being in where clause.
IMHO, it is wrong: in case there is no match, shall return null or
empty array – not remove the result from the set!!!
Is this a collateral effect of using regexp_matches in columns?
If yes, shall not this information be BOLD RED FLASHING in
documentation (or it is already, and some kind sould would point me
where)?
https://www.postgresql.org/docs/9.4/static/functions-matching.html
I see - I always believed that this page was related to WHERE clause or using functions in the PostgreSQL way (which is, in your turn, a alternative to "from" syntax) - not for the select clause.
But now that you mention it, and re-reading all the information, I can understand the implications.
Nevertheless, would be nice to put a huge warning at the "String functions" page about this behavior...
Well the above page is pointed to in the string functions section:
https://www.postgresql.org/docs/9.4/static/functions-string.html
"regexp_matches(string text, pattern text [, flags text])
setof text[] Return all captured substrings resulting from matching a
POSIX regular expression against the string. See Section 9.7.3 for more
information."
Where 'Section 9.7.3' is a link to it. Not sure if that counts as a
warning though:)
"It is possible to force regexp_matches() to always return one row by using a
sub-select; this is particularly useful in a SELECT target list when you want all
rows returned, even non-matching ones:
SELECT col1, (SELECT regexp_matches(col2, '(bar)(beque)')) FROM tab; "
Thanks, this worked - as well removing the "regexp_matches" and using "SUBSTRING( text FROM pattern)".
I really appreciate your help.
Kind regards,
Edson Richter
-- First query (that is limiting results)
---------------------------------------------------------------------
select codigoocorrencia, datahoraocorrencia, datahoraimportacao,
observacao, regexp_matches(observacao, '\d\d/\d\d/\d\d\d\d')
from batchloteocorrencia
where codigoocorrencia = '091'
and observacao is not null
order by datahoraimportacao DESC
Total results = 59
--Second query (that is not limiting results, as I did
expect)---------------------------------------------------------------
----
select codigoocorrencia, datahoraocorrencia, datahoraimportacao,
observacao
from batchloteocorrencia
where codigoocorrencia = '091'
and observacao is not null
order by datahoraimportacao DESC
Total results = 3826
Why is that?
Regards,
Edson Richter
--
Adrian Klaver
adrian.klaver@xxxxxxxxxxx
--
Adrian Klaver
adrian.klaver@xxxxxxxxxxx
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