Re: Connecting a postgresql client to an oracle7 db

Domenique,

> Ah... Reading the FAQs of PostgresQL and learning that SQL was very
> standardized, I had thought I could write an application that could
> connect to any SQL-implementing database on our intranet.

You can. You just need to use each database's *external* interfaces,
through ODBC, JDBC, or similar data transmission tools. Psql, like
Microsoft's Query Analyzer, connects with the database at a more
"intimate" level where commands are sent directly in the database's
internal API ... which is *never* standard. But with Java, Perl, PHP,
C++ or COM you should ba able to write an application that connects to
all SQL databases.

HOWEVER, Postgres upholds only about 80% of the standard, and most
other databases have less. Oracle, for example, uses a completely
non-standard notation for Outer Joins that is not compatible with any
other database, nor will it recognize SQL standard syntax for Outer
Joins. This will remain a problem for you even when you use JDBC or
similar to connect.

If you are going to go ahead with this project, I suggest that you:
1. Read the various "porting" documents at
http://techdocs.postgresql.org/
2. Buy a copy of "SQL In a Nutshell" from O'Reilly, which has
feature-for-feature and command-by-command comparison of Postgres,
MySQL, Oracle, and SQL Server (though it is 1.5 years out of date).
3. REsearch on the Net. It may be that some kind of "database
compatibility layer" that allows you to use a single standard syntax
to address all of your databases exists somewhere, either as Open
Source or for a fee.
-Josh Berkus

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