[ic] multi database query clarification

[Jon Jensen]

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.

Jon

-- 
Jon Jensen
End Point Corporation
http://www.endpoint.com/