Techincaly it will be the same server, same connection string, same everything, but version and features.
But I would be concerned about the following statement from docu:
The duration of upgrade depends on the size, edition and number of
databases in the server. The upgrade process can run for hours to days
for servers especially for servers that has databases:
- Larger than 50 GB, or
- At a non-premium service tier
Which is kind of concerning.
What I would do, if possible is:
- Put my service into read-only mode (put on hold any writes to the DB)
- Create new db in same server from the existing one with the command - CREATE DATABASE AS COPY OF ...
- When creation of DB is ready, export the new db to backpac and delete the DB when export is ready.
- Perform upgrade.
In theory you could do the process without putting your system into Read-Only mode, but I am just taking more precautions measures.
And yes, you also have to aware that you are upgrading your Azure SQL DB Server not just a single Database.