Query existing DBLinks

You can query information about existing DBLinks from views.

Procedure

You can query the DBA_DB_LINKS, ALL_DB_LINKS, and USER_DB_LINKS views for information about DBLinks.

SELECT * FROM SYS.USER_DB_LINKS;

The query result is as follows:

+-----------+----------+----------+-----------------+------------------+---------------------+-----------+--------+----------------+-------+-----------+-------------+---------------------+--------------+----------------------+--------------+--------------+------------------+
| DB_LINK   | USERNAME | PASSWORD | CREDENTIAL_NAME | CREDENTIAL_OWNER | HOST                | CREATED   | HIDDEN | SHARD_INTERNAL | VALID | INTRA_CDB | TENANT_NAME | REVERSE_TENANT_NAME | CLUSTER_NAME | REVERSE_CLUSTER_NAME | REVERSE_HOST | REVERSE_PORT | REVERSE_USERNAME |
+-----------+----------+----------+-----------------+------------------+---------------------+-----------+--------+----------------+-------+-----------+-------------+---------------------+--------------+----------------------+--------------+--------------+------------------+
| OB_DBLINK | SYS      |  NULL    | NULL            | NULL             | xx.xx.xx.xx:2881    | 22-MAY-23 | NULL   | NULL           | YES   | NULL      | oracle001   | NULL                | NULL         | NULL                 | 0.0.0.0      |            0 | NULL             |
+-----------+----------+----------+-----------------+------------------+---------------------+-----------+--------+----------------+-------+-----------+-------------+---------------------+--------------+----------------------+--------------+--------------+------------------+
1 row in set

where:

• DB_LINK indicates the name of the DBLink.
• USERNAME indicates the username used to connect to the remote database by using the DBLink.
• HOST indicates the hostname (or IP address) used to connect to the remote database by using the DBLink.
• CREATED indicates the time when the DBLink was created.
• VALID indicates whether the DBLink is available. This field is used only for compatibility. The default value is YES.
• TENANT_NAME indicates the tenant name used to connect to the remote database by using the DBLink.
• REVERSE_HOST indicates the hostname (or IP address) used to connect to the local database from the remote database by using the DBLink. If the current DBLink does not support the reverse link feature, the value is 0.0.0.0.
• REVERSE_PORT indicates the port number used to connect to the local database from the remote database by using the DBLink. If the current DBLink does not support the reverse link feature, the value is 0.
• REVERSE_USERNAME indicates the username used to connect to the local database from the remote database by using the DBLink. If the current DBLink does not support the reverse link feature, the value is NULL.

For more information about fields in the DBA_DB_LINKS, ALL_DB_LINKS, and USER_DB_LINKS views, see DBA_DB_LINKS, ALL_DB_LINKS, and USER_DB_LINKS.

References

For more information about operations on DBLinks, see the following topics:

• Create a DBLink

• Use a DBLink to access data in a remote database

• Use a DBLink to modify data in a remote database

• Drop a DBLink