-- If you create a global dblink, you must use the systm or sys user, and add public before database. create public database link dblink1 connect to dbusername identified by dbpassword using '(DESCRIPTION =(ADDRESS_LIST =(ADDRESS =(PROTOCOL = TCP)(HOST = 192.168.1.1)(PORT = 1521)))(CONNECT_DATA =(SERVICE_NAME = orcl)))'; -- When the database parameter global_name=true, the database link name is required to be the same as the remote database name. The database global name can be found out with the following command select * from global_name; -- Querying, deleting and inserting data is the same as operating a local database, except that the table name needs to be written as "table name@dblink server". select xxx FROM table name@database link name; -- delete dblink drop /* public */ database link dblink1; -- create and delete synonyms create or replace synonym synonym name for table name; create or replace synonym synonym name for user.table name; create or replace synonym synonym name for table name@database link name; drop synonym synonym name; -- create and delete views create or replace view view name as (select field from user. table name @dblink1); drop view view name; -- Notice: -- Creating a DBLink is very simple, but there is a lock in the background during use. To view this lock, you can go to the console to see or query the database. -- Every time you use dblink to query, a connection will be created with the remote database, and dblink should not automatically release this connection. If you use dblink to query a lot, the number of connections in the web project will be insufficient, resulting in the system not running normally. cause the system to malfunction.