Обсуждение: RE: [HACKERS] SQL92

> > The SQL92 LIKE:
> >
> >     character-string-expression [NOT] LIKE pattern [ESCAPE
> > 'escape-char']
> >
> > allows only the special characters % and _
> >
> > You need The SQL3 SIMILAR
> >
> >     character-string-expression [NOT] SIMILAR TO pattern [ESCAPE
> > 'escape-char']
> >
> > in this case pattern can involve additional special characters, not
> just
> > % and _ as in LIKE, but every regular expression or
> "[character_set]"
> > like you said. (Refer to "A Guide to SQL Standard 4th edition
> > Date-Rarwen, page 505).
> >
> >      Jose'
> >
> >
>
> TODO item changed to:
>
>     * add SIMILAR to allow character classes, 'pg_[a-c]%'
So are we going to add the character class support to LIKE or SIMILAR or
both?  Just looking for clarification.  Or are we going to use the regex
code for both?
    -DEJ

> > > The SQL92 LIKE:
> > >
> > >     character-string-expression [NOT] LIKE pattern [ESCAPE
> > > 'escape-char']
> > >
> > > allows only the special characters % and _
> > >
> > > You need The SQL3 SIMILAR
> > >
> > >     character-string-expression [NOT] SIMILAR TO pattern [ESCAPE
> > > 'escape-char']
> > >
> > > in this case pattern can involve additional special characters, not
> > just
> > > % and _ as in LIKE, but every regular expression or
> > "[character_set]"
> > > like you said. (Refer to "A Guide to SQL Standard 4th edition
> > > Date-Rarwen, page 505).
> > >
> > >      Jose'
> > >
> > >
> >
> > TODO item changed to:
> >
> >     * add SIMILAR to allow character classes, 'pg_[a-c]%'
> So are we going to add the character class support to LIKE or SIMILAR or
> both?  Just looking for clarification.  Or are we going to use the regex
> code for both?

No idea.  It is just a valid TODO item.

--
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> >       * add SIMILAR to allow character classes, 'pg_[a-c]%'
> So are we going to add the character class support to LIKE or SIMILAR
> or both?  Just looking for clarification.  Or are we going to use the
> regex code for both?

I would expect us to stay compatible with the standard for LIKE, and
perhaps have a superset of the SQL3 (draft) standard for SIMILAR. I'd
expect it to be a candidate for v6.5, or perhaps for v6.4.x.

But I'm not doing the work, and whoever does has a much stronger vote :)

               - Tom