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From: jian he <[email protected]>
To: David G. Johnston <[email protected]>
Cc: PostgreSQL-development <[email protected]>
Subject: Re: add function argument name to substring and substr
Date: Wed, 19 Mar 2025 09:19:42 +0800
Message-ID: <CACJufxFpzqdfYvsj2iWhtemRyPSB5O7_gb9vRd7cE1ZcVvmZnw@mail.gmail.com> (raw)
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On Wed, Mar 19, 2025 at 8:19 AM David G. Johnston
<[email protected]> wrote:
>
> The vast majority of examples throughout the manual use traditional function call syntax  func_name(arg1, arg2, etc.);  I'd rather keep with convention 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 spending some time in our Tutorial adding some more examples with these alternative 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 Syntax 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 ) → text
Extracts the first substring matching POSIX regular expression; see
Section 9.7.3.
substring('Thomas' from '...$') → mas
```

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


if we add to
``substring ( string text, pattern text ) → 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

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