I installed SQL Server 2008 on Windows 7. Then I created a database. After 2 days I reinstalled Windows and SQL Server.

Now I am trying to attach my database file, but I have encountered the error below.

I think that the files are like an attached file and I can't attach them. What is difference between an attached file and a non-attached file? How can I attach this file? Please Help Me.

Error Text: TITLE: Microsoft SQL Server Management Studio

Attach database failed for Server 'AMIR-PC'. (Microsoft.SqlServer.Smo)

For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&ProdVer=10.50.1600.1+((KJ_RTM).100402-1540+)&EvtSrc=Microsoft.SqlServer.Management.Smo.ExceptionTemplates.FailedOperationExceptionText&EvtID=Attach+database+Server&LinkId=20476

------------------------------ ADDITIONAL INFORMATION:

An exception occurred while executing a Transact-SQL statement or batch. (Microsoft.SqlServer.ConnectionInfo)

Unable to open the physical file "F:\Company.mdf". Operating system error 5: "5(Access is denied.)". (Microsoft SQL Server, Error: 5120)

For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft+SQL+Server&ProdVer=10.50.1600&EvtSrc=MSSQLServer&EvtID=5120&LinkId=20476

1 Answer 1


If you're getting that error then your database is not attached and thus won't be in the list of databases on your server instance. And thus, since it is not attached to begin with, it cannot be detached.

The account that your SQL Server instance is running as does not have the file system permissions to access the data file you want to attach. You need to change the permissions on the data file before you can attach that database.

During SQL Server installation several groups are created so that security is set on SQL Server filesystem resources appropriately. Most likely the permissions left on F:\Company.mdf are related to the accounts / groups from your previous installation of Windows. Now that you've reinstalled Windows and SQL Server these accounts have been recreated with new security identifiers (SIDs). Even if the new new accounts / groups are named the same as they were in your previous installation the SIDs will be different and the SID is how a security principal is identified.

Reset the permissions on F:\Company.mdf and the corresponding log (.ldf) file (maybe it's F:\Company.ldf?) and then try to reattach the file.

  • Yes. That is Right! But I dont Know hot change Database Files Permision!
    – Amir
    Jun 30, 2012 at 21:03
  • Yes. That is Right! But I dont Know how to change Database Files permssion ! ? ! ? does this permission must be changed in sql server? Or in Windows permission? How to change database engine permission?
    – Amir
    Jun 30, 2012 at 21:34
  • Windows permissions. At the filesystem. You need to change the Windows permissions so that the account SQL server is running a can access it.
    – squillman
    Jul 1, 2012 at 2:15

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