Oracle – When to Install Oracle Database Client

It's not clear from your question what brand of database you are connecting to. I will assume it's Oracle. You need this information:

• name of the server the database is on
• name of the database --sometimes called a service name
• is the database parameter db_domain configured with a value? (usually the domain name)
• the port the database listener is using (usually port 1521)
• a user and password, be good and don't connect as sys

Let's try the easiest way, connecting directly

• open toad
• select session/new connection from the menu
• select the "Direct" tab from the right side and enter
  • User and password
  • Host = machine name of the database server
  • Port = 1521
  • Service Name = Name of the database
• connect as normal if you are not connecting as sys
• ensure that the Installed clients picks up the correct install of your Oracle client

and....press connect.

This is the easiest way. More involved is adding the name of the database to the TNSNames in your oracle client. Another good check is to log onto the server where the database is and start a DOS command line window. Enter lsnrctl status . This will give you the database name and port and if the listener is ready to receive connections.

SQL Developer is using the so called "thin driver".

For this the JDBC driver (a file named ojdbc6.jar) implements the complete Oracle network protocol which is usually handled by the Oracle client. It could use the another implementation: the "OCI" (or "thick") driver which would require an Oracle client to be installed. That would be necessary if e.g. Transparent Application Failover in a RAC is required.

This is not something specific to SQL Developer but to any Java application using JDBC to connect to the database.