Posted by Michael Fesser on 06/19/07 23:22

..oO(Marcus)

>Whenever the PHP documentation references the optional link_identifier
>parameter in many mysql related functions (such as mysql_query,
>mysql_insert_id, etc.), it says:
>
>"The MySQL connection. If the link identifier is not specified, the last
>link opened by mysql_connect() is assumed. If no such link is found, it
>will try to create one as if mysql_connect() was called with no
>arguments. If by chance no connection is found or established, an
>E_WARNING level warning is generated."
>
>I know that functions such as mysql_insert_id are connection specific,
>but I have not been able to find any info explicitly stating that it is
>also connection specific when link_identifier is omitted.

If the link identifier is omitted, the statement from above applies,
i.e. the last opened link from within the same script will be used.

>I am about
>99% sure that it would still be connection specific because otherwise
>these functions would be pretty useless, but could someone please
>confirm this?

It is always connection-specific.

>I just want to avoid the scenario where persons A and B are accessing
>the same script, but by the time person A runs mysql_insert_id (or some
>other mysql function), person B's connection is technically "the last
>link opened by mysql_connect()".

This can't happen. Two people accessing the site at the same time means
two different script calls, two different mysql_connect() calls, hence
two different connections => mysql_insert_id() will work as expected.

The "last link opened by mysql_connect()" doesn't mean all opened links
from all running scripts on the server, it just refers to the currently
running script from the current user.

>In other words, I want to make sure
>that I can omit the link_identifier and still be confident that
>different connections will not affect each other.

Connections from different scripts won't affect each other.

Micha

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