SQL Server: allow users to specify they're using SQL Azure

[roji]

30163 is about allowing users to specify their SQL Server compatibility level, allowing them to say they're using an old database which doesn't support some feature (e.g. OPENJSON). We could also allow users to inform us that they're targeting SQL Azure. This could have the following effects:

• We could automatically set up the Azure SQL retrying strategy.
• We could automatically set the compatibility level listed in the docs. However, note that old databases aren't automatically upgraded to new compat levels, so there are Azure SQL databases with lower levels out there (source. Also, we've made the decision to go with the latest compatibility level as our default, so it doesn't really matter anyway.

Think specifically about the impact on people testing against non-Azure SQL, which may need to configure differently for testing vs. production etc.

[ErikEJ]

For the first item you could also execute:

 SELECT ServerProperty('EngineEdition')

and check for 5, 8 or 11

https://learn.microsoft.com/en-us/sql/t-sql/functions/serverproperty-transact-sql?view=sql-server-ver16

[roji]

@ErikEJ we generally don't do runtime checking of database capabilities like this - otherwise we could have also attempted to check the database's compatibility level (#30163) rather than requiring users to explicitly configure it. One reason for that is that we don't always have a database to connect to (e.g. when generating SQL scripts for migrations).