SPContentDatabase.Update Method

Saves the state of the content database and propagates changes in it to all the computers in the server farm, after first verifying that the content database is attached to the farm.

Namespace:  Microsoft.SharePoint.Administration
Assembly:  Microsoft.SharePoint (in Microsoft.SharePoint.dll)
Available in Sandboxed Solutions: No

public override void Update()

This override will call the base Update(), unless the content database is unattached, in which case it throws an exception.