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From: jian he <jian.universality@gmail.com>
Date: Wed, 19 Mar 2025 09:19:42 +0800
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 <CACJufxFpzqdfYvsj2iWhtemRyPSB5O7_gb9vRd7cE1ZcVvmZnw@mail.gmail.com>
Subject: Re: add function argument name to substring and substr
To: "David G. Johnston" <david.g.johnston@gmail.com>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
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On Wed, Mar 19, 2025 at 8:19=E2=80=AFAM David G. Johnston
<david.g.johnston@gmail.com> wrote:
>
> The vast majority of examples throughout the manual use traditional funct=
ion call syntax  func_name(arg1, arg2, etc.);  I'd rather keep with convent=
ion than start to scatter about alternative syntax choices just to give the=
 random reader who happens upon this fairly esoteric part of the manual the=
 benefit of seeing their options.  If that is a goal, then I'd suggest spen=
ding some time in our Tutorial adding some more examples with these alterna=
tive forms to people looking to be exposed to new things in the place they'=
d go to look for them.  They probably won't learn about them from the Synta=
x section.
>
> On the plus side, I agree now we should add:
> substring(string text, pattern text[, escape-character text])
> to Table 9.10
>
in Table Table 9.9 we have
```
substring ( string text FROM pattern text ) =E2=86=92 text
Extracts the first substring matching POSIX regular expression; see
Section 9.7.3.
substring('Thomas' from '...$') =E2=86=92 mas
```

can we change to
substring ( string text FROM pattern text ) =E2=86=92 text
substring ( string text, pattern text ) =E2=86=92 text
Extracts the first substring matching POSIX regular expression;
the second format is not standardized. see Section 9.7.3.
substring('Thomas' from '...$') =E2=86=92 mas


if we add to
``substring ( string text, pattern text ) =E2=86=92 text``
Table 9.10,
then maybe it feels like duplication?
(same function in Table 9.9, Table 9.10, then we also need some words
saying that they are the same)

I do realized we have brief explanation about Table 9.9 and Table 9.10 in
second paragraph of
https://www.postgresql.org/docs/current/functions-string.html