A link qualifier can be appended to a global database link. While one global database link per database is recommend, there is no limit on the number of link qualifiers that may be added. Link qualifiers are appended to global database links to provide alternate settings for the database user name and password credentials. Link qualifiers are primarily for older Oracle database environments where multiple database links are used. Rather than use multiple database links, multiple link qualifiers can be created for a database link.
To create a link qualifier: