Question: I have a database that has a 28gig transaction log file. Recovery mode is simple. I just took a full backup of the database, and then ran both:

`backup log dbmcms with truncate_only`

DBCC SHRINKFILE ('Wxlog0', TRUNCATEONLY)

The name of the db is db\_mcms and the name of the transaction log file is Wxlog0. 

Neither has helped. I'm not sure what to do next.

Answer: 
I've had the same issue in the past. Normally a shrink and a trn backup need to occur multiple times. In extreme cases I set the DB to "Simple" recovery and then run a shrink operation on the log file. That always works for me. However recently I had a situation where that would not work. The issue was caused by a long running query that did not complete, so any attempts to shrink were useless until I could kill that process then run my shrink operations. We are talking a log file that grew to 60 GB and is now shrunk to 500 MB.

Remember, as soon as you change from FULL to Simple recovery mode and do the shrink, dont forget to set it back to FULL. Then immediately afterward you must do a FULL DB backup.
You cannot shrink a transaction log smaller than its initially created size.