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Saturday, May 18, 2013

Creating an Oracle Database Connection

Database connections can be created and saved for reuse. Figure below shows the window where connections can be defined. To reach this window, click the “+” symbol visible on the Connections tab. The username and password must both be supplied, but only the username will be saved unless the Save Password check box is selected. Saving a password means that future connections can be made without any password prompt. This is convenient but highly dangerous if there is any possibility that the computer you are working on is not secure. In effect, you are delegating the authentication to your local operating system: if you can log on to that, you can log on to the database.

The Connection Type radio buttons let you choose between three options:
  • Basic This prompts for the machine name of the database server, the port on which the database listener will accept connection requests, and the instance (the SID) or the service to which the connection will be made.
  • TNS If a name resolution method has been configured, then an alias for the database can be entered, rather than the full details needed by the Basic option.
  • Advanced This allows entry of a full JDBC (Java Database Connectivity) connect string. This is completely Oracle independent and could be used to connect to any database that conforms to the JDBC standard.
Selecting Basic requires the user to know how to connect to the database; selecting TNS requires some configuration to have been done on the client machine by the database administrator, in order that the alias can be resolved into the full connection details.
After you enter the details, the Test button will force SQL Developer to attempt a logon. If this returns an error, then either the connection details are wrong, or there is a problem on the server side. Typical server-side problems are that the database listener is not running, or that the database has not been started. Whatever the error is, it will be prefixed with an error number.

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