Oracle db_link Summary

Dblink Overview

A database link is a schema object in one database that enables you to access objects on another database. The other database need not be an Oracle database system.

Syntax/writing

Create [Shared] [public] database linkDblink [Connect {CURRENT_USER |UserIdentifiedPassword[Dblink_authentication] } | Dblink_authentication ]... [UsingConnect_string];

keyword public. If the default db_link created by default is omitted, it cannot be shared by other users and can only be used by itself. shared. This keyword indicates global sharing of the created db_link (related to the session). To use this keyword, db_link_authentication is required (see example 2). connect to, specifying the connection tag to connect to the remote database CURRENT_USER: use the information of the current user to establish a remote database. This must ensure that the current user exists and is valid in the remote database. using: Specify the address of the remote database (example)

Example 1 Create database link db_link_name Connect to remote_user_code identified by user_password Using '1970. 168.0.8: 192/Sid '; Example 2 Create shared database_link db_link_name Connect to remote_user_code_1 identified by user_password_1 Authenticated by remote_user_code_2 identified by user_password_2 Using '1970. 168.0.8: 192/Sid' Example 2_1 Create shared database_link db_link_name Authenticated by remote_user_code_2 identified by user_password_2 Using '1970. 168.0.8: 192/Sid' Note,In Example 2, two remote_user_codes are remote_user_code_1 \ remote_user_code_2. Because the shared keyword must have authentication, connect to can be omitted (Example 2_1).

Usage

Select count (*) from user_tables @ db_link_name; Update sys_user @ db_link_name set user_name = '001' where age> 50 Insert into sys_user @ db_link_name (user_id, user_name, age) values (001, '001', 51) Delete from user_tables @ where user_id = '001'

References

• Oracle documentation Library
• Http://download.oracle.com/docs/cd/E11882_01/server.112/e17118/statements_5005.htm#SQLRF01205