[ic] multi database query clarification

Paul Jordan paul at gishnetwork.com
Wed Jan 19 01:11:56 UTC 2011

> From: jon at endpoint.com
> On Tue, 18 Jan 2011, Paul Jordan wrote:
> > However, if I create a JOIN that spans this new table (in Database B)
> > and any table in Database A, there are problems. IC will only recognize
> > one table. The fix is to use the full dsn... FROM databaseB.newtable AS
> > foo, etc.
> That's a nonstandard MySQLism. Normal Perl DBI connections work for only a
> single database, and that's what Interchange assumes.
> Really the problem is that what MySQL calls a "database" is called a
> "schema" in other databases such as Postgres and Oracle. It's possible to
> reference tables from different schemas in a single connection, but not
> from different databases. (Short of custom functions that hack around
> that.)
> Interchange's database abstraction layer comes from a different era and it
> would be simpler for most purposes now if it defined connection handles
> separate from tables. But that's another discussion.

Your explanation sounds reasonable, thank you. I should have really been calling them Schemas. Mysql's admin software (QB, workbench, etc) does refer to them as Schemas and I do understand them as such so that was just my misreferene there.
Thanks again,

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