Oracle-dblink

1. Create a previous job

Before creating a dblink, first check whether the user has the appropriate permissions. For a specific user, after logging in using sqlplus user/pwd, execute the following statement:

Copy the code The code is as follows:

select * from user_sys_privs t where t.privilege like upper('%link%');

Under the sys user, the displayed result is:

SYS CREATE DATABASE LINK NO
SYS DROP PUBLIC DATABASE LINK NO
SYS CREATE PUBLIC DATABASE LINK NO

It can be seen that dblink has three permissions in the database:

CREATE DATABASE LINK--The created dblink can only be used by the creator, other users cannot use
CREATE PUBLIC DATABASE LINK--public means that all users of the created dblink can use
DROP PUBLIC DATABASE LINK--Delete the specified dblink

If you want to change the permissions of a user, you need to modify it under the sys user:

Copy the code The code is as follows:

grant CREATE PUBLIC DATABASE LINK，DROP PUBLIC DATABASE LINK to scott;

There are two ways to view dblink, as follows:

①.

Copy the code The code is as follows:

select owner,object_name from dba_objects where object_type='DATABASE LINK';

②.

Copy the code The code is as follows:

select * from dba_db_links;

2. Create dblink

 
        create 
        public 
        database 
        link LINK_NAME 
       
        connect 
        to 
        USRNAME identified  
        by 
        "PASSWORD" 
       
        using  
       
        '(DESCRIPTION =(ADDRESS = (PROTOCOL = TCP)(HOST = XXX.XXX.XXX.XXX)(PORT = 1521)) 
       
        (CONNECT_DATA =(SERVER = DEDICATED)(SERVICE_NAME = XXX)) 
       
        )' 
        ;

Note: using is followed by a string, in which there must be no unnecessary spaces, otherwise an error ORA-12514 will occur . In the above code, for the convenience of reading, a line break may appear, which may cause errors, so use It's ok to remove the spaces.

Here LINK_NAM is a custom name; USERNAME and PASSWORD are the user name and password in the specified oracle database, SERVICE_NAME can be obtained by the following statement if you are not sure:

Copy the code The code is as follows:

show parameter service_names;

Copy the code The code is as follows:

select name,value from v$parameter where name='service_names'

3. Use of dblink

The use of dblink is relatively simple. Change the table name when accessing a local table to the following format: [user.]table@link_name.

Copy the code The code is as follows:

select studentid from abc.studeng@abc_ten;

4. Delete dblink

After determining the name of the dblink to be deleted, you can delete it directly through the drop command:

Copy the code The code is as follows:

drop public database link abc_ten;

I hope that this article will be helpful to everyone in Oracle database programming.

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