Understanding of database link and the same term

Database link Function
Database link, which makes it easier for a database to access another database (both local and remote). At the beginning, many people may misunderstand it, it is actually created locally. That is, the database connection is just a shortcut to connect to another database.

I. zhujianDatabase Link

First:

1. Use Net manager to configure remote services and listeners based on remote information.Program.
2. Create public database link fwq12

Connect to fzept identified by Neu
Using   ' Fjept '   // Fjept is the service name Just configured

Second:
Directly create a link:

Create database link linkfwq
Connect to fzept identified by Neu
Using   ' (Description =
(Address_list =
(Address = (Protocol = TCP) (host =   192.168 . 254.132 ) (Port =   1521 ))
)
(CONNECT_DATA = (Server = Dedicated)
(SERVICE_NAME = SH2)
)
) ' ;

Note: If you have created a connector in the tnsnames. ora file, you do not need to create a DB link.
If you create a global dblink, you must use the mongom or sys user to add public to the database.

Ii. Use dB Link

Query tables in a remote database

Select ...... From table name @ Database Link name;

Querying, deleting, and inserting data are the same as operating a local database, except that the table name must be written as "table name @ dblink name.

Iii. Remove dB Link Delete dblink: Drop public database link linkfwq.

3. Synonyms

Create:

Create synonym name for table name;
Create synonym name for table name @ Database Link name;

Except:

Drop Synonym Synonym name ; Exam: http://www.techrss.cn/html/2008/03-12/77859.htm