Detecting auto-incrementing primary keys

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Daniel Kasak - 30 Jun 2008 09:25 GMT

Hi all.

I'm looking for a *portable* way to detect auto-incrementing primary
keys. Is there one?

I'm using $dbh->primary_key_info to fetch details about column(s) that
are participating in primary keys, but this doesn't mention whether
they're auto-incrementing or not, and I must also know this.

I realise I can do $dbh->column_info to fetch info on columns, but:

a) Not all servers support this ( SQLite, which I have to support,
doesn't )

b) It's not very portable - each server seems to say something slightly
different.

Any ideas?

Thanks.

Dan

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Greg Sabino Mullane - 30 Jun 2008 14:42 GMT

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> I'm looking for a *portable* way to detect auto-incrementing primary
> keys. Is there one?

No - because there is no universal concept of an "auto-incrementing"
primary key. MySQL and SQLite have a specific column modifier
called AUTOINCREMENT. Postgres uses sequences and a default value.
Oracle uses sequences and a trigger. And so on. Perhaps if you explain
what exactly you are trying to do, another solution (such as
$dbh->last_insert_id() perhaps?) may present itself.

- --
Greg Sabino Mullane greg@turnstep.com
PGP Key: 0x14964AC8 200806300940
http://biglumber.com/x/web?pk=2529DF6AB8F79407E94445B4BC9B906714964AC8

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C.J. Adams-Collier - 30 Jun 2008 20:42 GMT

I expect he was looking for an abstraction around the concept of
auto-increment primary key / sequence, etc.

Dan,

As Greg mentioned, since 1.38, DBI has specified a C<last_insert_id>
method. The docs recommend caution when using this method, however,
since its operation may or may not be defined depending on which DBD
driver used.

http://search.cpan.org/~timb/DBI-1.605/DBI.pm#last_insert_id

Which driver(s) do you intend to use?

Cheers,

C.J.

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Daniel Kasak - 06 Jul 2008 03:09 GMT

Damned anti-spam server thinks I'm a spammer ...
... resending with my ISP's mail server.

See attached ...

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Detecting auto-incrementing primary keys