Dynamic connection string is a Great feature in RS2005. When you use shared datasources, you HARDCODE the Servername and Database name in there which you cannot change.
What if you want to run the same report against a different Server and a different database? you have to create another dataset and tie that with the new report and re-deploy and now ure creating multiple reports for each server/database.
With Dynamic Connection string, You just need one report deployed on a WebServer.
you can run that report against any database on anyserver by simply passing in the servername and databasename.
That one report will generate different data each time you run the report against a different database.
What if you have 5 databases? you can create only one connection string in a dataset and thats hardcoded and cannot be changed when you deploy it. so that report will run against connectionstring/database you hardcoded.
With Dynamic connection string, nothing is hardCoded.. you simple pass it the Server and database names and it will show you the results.
Just One report against 100 databases!