sometimes, we need backup content database about sharepoint site, then restore it one day. of course, we can backup the contetn database in SQL, then restore it in Sharepoint Central Admin, but it often failed to restore DB using Central Admin, I didn‘t find the reason.so I had to find a good way to around it. the best is Powershell cmd.
here is my steps:
1. firsty, we need dismount the old DB
Dismount-SPContentDatabase “OldContentDatabaseName"
2. then, attach the newe DB
Mount-SPContentDatabase Migrated_WSS_Content -DatabaseServer "SQLServerClusterName" -WebApplication <a target=_blank href="http://siteurl">http://siteurl</a>
Restore content database in sharepoint
原文：http://blog.csdn.net/tristan_dong/article/details/39644111