How can I generate customer reports by SQL?
In another way speaking, how to connect the Collaborator database if I just know the web link? Can I only contact the Collaborator server administrator?
For external databases(MySQL, SQLServer, Oracle) you will need a Client applications from those vendors, and the hostname, port, username, password to connect to the database.
So, I don't think it will be possible to connect using only the "web link".
If Collaborator is using the embedded database, you can follow the instructions in this article, https://smartbear-cc.force.com/portal/KbArticleViewer?name=How-to-view-and-edit-the-hsql-embedded-da...
In any case, if you are not an administrator, that has access to that information, you will not be able to connect to the database.