Re: [HACKERS] just another standards question

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От Michael Meskes
Тема Re: [HACKERS] just another standards question
Дата
Msg-id 199803231552.QAA22522@gauss.topsystem.de
обсуждение исходный текст
Ответ на Re: [HACKERS] just another standards question  ("Thomas G. Lockhart" <lockhart@alumni.caltech.edu>)
Список pgsql-hackers
Thomas G. Lockhart writes:
> I had found a draft of the SQL92 standard on-line somewhere many months
> ago; don't remember where. It is ~1.6MB uncompressed, probably much
> smaller compressed; do you want me to send you a copy?

Yes, please.

> Anyway, it looks like Informix and Sybase have it right:
>
>   4.18.3  Indicator parameters
>
>   An indicator parameter is an integer parameter that is specified
>   immediately following another parameter. Its primary use is to
>   indicate whether the value that the other parameter assumes or
>   supplies is a null value. An indicator parameter cannot immediately
>   follow another indicator parameter.

Okay, that works completely.

>   The other use for indicator parameters is to indicate whether
>   string data truncation occurred during a transfer between a host
>   program and an SQL-implementation in parameters or host variables.
>   If a non-null string value is transferred and the length of the
>   target data item is sufficient to accept the entire source data
>   item, then the indicator parameter or variable is set to 0 to in-
>   dicate that truncation did not occur. However, if the length of
>   the target data item is insufficient, then the indicator parame-
>   ter or variable is set to the length of the source data item (in
>   characters or bits, as appropriate) to indicate that truncation
>   occurred and to indicate the original length in characters or bits,
>   as appropriate, of the source.

So I have to set the indicator also during writes? That is if I insert
string "foobar" into char(3), do I have to set the indicator to 3?

Michael

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