Create database link

Delete database link: drop database link linkname;

Create database link:
Create database link linkname
Connect to username
Identified by password
Using 'Connection string ';


If you want to create a global link, you need to use the Keyword: public

Create public database link linkname
Connect to username
Identified by password
Using 'Connection string ';


Connection string can be in two forms:
1. the name configured in the file tnsnames. ora:
For example:
CDRDL =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP) (HOST = 10.147.129.29) (PORT = 2521 ))
)
(CONNECT_DATA =
(SERVICE_NAME = cdrdb)
)
)
In this case, you can write it as follows:
Create database link linkname
Connect to username
Identified by password
Using 'cdrdl ';

2. You can also directly use the string after '=,
For example:
Create database link linkname
Connect to username
Identified by password
Using '(DESCRIPTION = (ADDRESS_LIST = (ADDRESS = (PROTOCOL = TCP) (HOST = 10.147.129.29) (PORT = 2521) (CONNECT_DATA = (SERVICE_NAME = cdrdb )))';