On UNIX™, LD_LIBRARY_PATH (or equivalent) must hold the
path to find the Oracle® client library. On
Microsoft Windows, the PATH environment variable must contain the path to Oracle client
library.
In an Oracle Database Server context, make sure that ORACLE_HOME and ORACLE_SID environment
variables are properly set.
With an Oracle Instant Client environment, define the TNS_ADMIN variable to find the
configutation files.
The TNSNAMES.ORA file must define the database server identifiers for remote connections (the
Oracle Listener must be started on the
database server to allow remote connections).
The SQLNET.ORA file must define network settings for remote connections.