I run a server with around 400+ databases which have a similar database schema, if only to deploy a custom clr/.internet user defined function for them all, can there be any easy method of doing this, or must it's done individually to every database?

Sincerely, Wayne

I believe should you create it in master (in MSSQL) it may be recommended from the other db for the reason that instance. Certainly appears to dedicate yourself Saved Procs anyway.

I ought to include that this only works when the databases are on a single server instance...

You can write a little application to deploy the udf to online resources each SQL server instance if all 400 reside on multiple servers.

i'd just produce a dynamic script to produce it on each database. but next i'd place it within the modal databases to ensure that brand new databases are produced by using it.

you might make use of the same script to push out changes when the function ever will get modified.