Database links are network objects stored in the local database or in the network definition that identify a remote database, a communication path to that database, and optionally, a user name and password. Once defined, the database link is used to access the remote database. Oracle Database supports connected user links, fixed user links, and current user links.
Enterprise users can use all three types of the following database links:
Connected user links are accessed by a local user who has an account on the remote server.
Fixed user links contain a user name and password as part of the link definition.
Current user database links allow enterprise users to access objects on remote databases without passing authentication information during link execution, or storing authentication information in the link definition.
They require SSL for the database network connections, which means public key infrastructure (PKI) credentials must be obtained and maintained for the databases. Current user database links can be used to connect to the remote database only as an enterprise user.
See Also:
"About Using Current User Database Links for Enterprise User Security" for detailed information about creating and using current user database links
Oracle Database Administrator's Guide for information about all of the different types of database links supported by Oracle Database