[ic] multi database query clarification

Jon Jensen jon at endpoint.com
Wed Jan 19 01:01:52 UTC 2011

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 

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 Jensen
End Point Corporation

More information about the interchange-users mailing list