Re: Regular expression question with Postgres
| От | Mike Christensen |
|---|---|
| Тема | Re: Regular expression question with Postgres |
| Дата | |
| Msg-id | CABs1bs0L5kghZKe8B1tT-v2DB9hUMgYFNy082gjkUfEx1ygBWA@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Regular expression question with Postgres (David G Johnston <david.g.johnston@gmail.com>) |
| Список | pgsql-general |
Yea seems right. I was testing the expression on Rubular (Which uses the Ruby parser) and it worked. I guess Ruby allows this non-standard expression with the missing lower bounds. Every reference I could find, though, agrees only the upper bound is optional.
On Thu, Jul 24, 2014 at 1:42 PM, David G Johnston <david.g.johnston@gmail.com> wrote:
Mike Christensen-2 wroteApparently since "{,#}" is not a valid regexp expression the engine simply> I'm curious why this query returns 0:
>
> SELECT 'AAA' ~ '^A{,4}$'
>
> Yet, this query returns 1:
>
> SELECT 'AAA' ~ '^A{0,4}$'
>
> Is this a bug with the regular expression engine?
interprets it as a literal and says 'AAA' != 'A{,4}'
http://www.postgresql.org/docs/9.3/interactive/functions-matching.html#FUNCTIONS-POSIX-REGEXP
Table 9-13. Regular Expression Quantifiers
Note the all of the { } expressions have a lower bound (whether explicit or
implied).
David J.
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