What does "Drop Connections" and "Update Statistics" in the "Detach Database" dialog do? As a testing phase I have installed the evaluation version of SQL Server 2014 Enterprise Edition. 

When I detach a database through SQL Server Management Studio, I see two options:


Drop Connections
Update Statistics




Both options will detach the database from the SQL Server Instance.  What is the difference between the two options?
Drop Connections will force the database into Single User mode before detaching the database, thereby forcing all users to disconnect.  If you don't check-mark that option, and users are connected to the database, the database will not be detached.

Update Statistics will refresh any out of date statistics before detaching the database.  If you leave this option un-checked, statistics objects will remain as they were at the time you detached the database. 

Microsoft has an excellent article with more details on MSDN.