How can I access remote Oracle databases from the R/3 system?
In addition to standard solutions such as database links, you can – as of R/3 4.0B – define a secondary database connection (as described in Notes 323151 and 339092) to access remote Oracle databases. This is a good solution because you do not need to make any changes at Oracle level (except for adjustments to tnsnames.ora) and the connection is set up in the same way as the primary database connection.