I was wondering if it is possible to add/update/delete an SQL Server database table, as well as an Informix database table at the same time.
Both databases will have the same table (data and all), so the query would only change just based on which database it is going to. For some reason, we need the data inside both databases and kept up in real time.
Is it possible to do this with a SQL Trigger or maybe a SProc?
Any insight of how to do this, or a push in the right direction would be very much appreciated.
Doing a synchronous update, ie. a distributed transaction by using a linked server, possible for a trigger, while technically possible, I would definitely advise against it. Aaron brings the issue of how reliable XA in general is, but my point is different: availability. Your update in SQL Server will fail if it cannot connect and update in Informix. Downtime (patching, maintenance, not to mention disasters) of the Informix site will imply downtime of the SQL Server site, driving your five 9's toward nine 5's quite fast... This is why I strongly advocate decoupling the application of updates. Transactional Replication is such an example of decoupling and it supports heterogenous environments (ie. Informix client downstream to accept the changes).
You will have a delay of update visibility (state in SQL Server will be reflected in Informix after delay that can be milliseconds, seconds, minutes, even hours in a bad day). And the updates are one way, nothing flows back from Informix to SQL Server. But doing master-master replication in an heterogeneous environment is something that not even Chuck Norris would attempt, just saying.