Attach a Database

Applies to: yesSQL Server (all supported versions)

This topic describes how to attach a database in SQL Server by using SQL Server Management Studio or Transact-SQL. You can use this feature to copy, move, or upgrade a SQL Server database.


  • The database must first be detached. Attempting to attach a database that has not been detached will return an error. For more information, see Detach a Database.

  • When you attach a database, all data files (MDF and LDF files) must be available. If any data file has a different path from when the database was first created or last attached, you must specify the current path of the file.

  • When you attach a database, if MDF and LDF files are located in different directories and one of the paths includes \\?\GlobalRoot, the operation will fail.

Is Attach the best choice?

We recommend that you move databases by using the ALTER DATABASE planned relocation procedure instead of using detach and attach, when moving database files within the same instance. For more information, see Move User Databases.

We don't recommend using detach and attach for Backup and Recovery. There are no transaction log backups, and it's possible to accidentally delete files.


File access permissions are set during a number of database operations, including detaching or attaching a database. For information about file permissions that are set whenever a database is detached and attached, see Securing Data and Log Files from SQL Server 2008 R2 Books Online (Still a valid read!)

We recommend that you do not attach or restore databases from unknown or untrusted sources. Such databases could contain malicious code that might execute unintended Transact-SQL code or cause errors by modifying the schema or the physical database structure. Before you use a database from an unknown or untrusted source, run DBCC CHECKDB on the database on a nonproduction server and also examine the code, such as stored procedures or other user-defined code, in the database. For more information about attaching databases and information about changes that are made to metadata when you attach a database, see Database Detach and Attach (SQL Server).



Using SQL Server Management Studio

To Attach a Database

  1. In SQL Server Management Studio Object Explorer, connect to an instance of the SQL Server Database Engine, and then click to expand that instance view in SSMS.

  2. Right-click Databases and click Attach.

  3. In the Attach Databases dialog box, to specify the database to be attached, click Add; and in the Locate Database Files dialog box, select the disk drive where the database resides and expand the directory tree to find and select the .mdf file of the database; for example:

    C:\Program Files\Microsoft SQL Server\MSSQL13.MSSQLSERVER\MSSQL\DATA\AdventureWorks2012_Data.mdf


    Trying to select a database that is already attached generates an error.

    Databases to attach
    Displays information about the selected databases.

    <no column header>
    Displays an icon indicating the status of the attach operation. The possible icons are described in the Status description, below).

    MDF File Location
    Displays the path and file name of the selected MDF file.

    Database Name
    Displays the name of the database.

    Attach As
    Optionally, specifies a different name for the database to attach as.

    Provides a drop-down list of possible database owners from which you can optionally select a different owner.

    Displays the status of the database according to the following table.

    Icon Status text Description
    (No icon) (No text) Attach operation has not been started or may be pending for this object. This is the default when the dialog is opened.
    Green, right-pointing triangle In progress Attach operation has been started but it is not complete.
    Green check mark Success The object has been attached successfully.
    Red circle containing a white cross Error Attach operation encountered an error and did not complete successfully.
    Circle containing two black quadrants (on left and right) and two white quadrants (on top and bottom) Stopped Attach operation was not completed successfully because the user stopped the operation.
    Circle containing a curved arrow pointing counter-clockwise Rolled Back Attach operation was successful but it has been rolled back due to an error during attachment of another object.

    Displays either a blank message or a "File not found" hyperlink.

    Find the necessary main database files. When the user selects an .mdf file, applicable information is automatically filled in the respective fields of the Databases to attach grid.

    Removes the selected file from the Databases to attach grid.

    " <database_name> " database details
    Displays the names of the files to be attached. To verify or change the pathname of a file, click the Browse button (...).


    If a file does not exist, the Message column displays "Not found." If a log file is not found, it exists in another directory or has been deleted. You need to either update the file path in the database details grid to point to the correct location or remove the log file from the grid. If an .ndf data file is not found, you need to update its path in the grid to point to the correct location.

    Original File Name
    Displays the name of the attached file belonging to the database.

    File Type
    Indicates the type of file, Data or Log.

    Current File Path
    Displays the path to the selected database file. The path can be edited manually.

    Displays either a blank message or a "File not found" hyperlink.

Using Transact-SQL

To attach a database

  1. Connect to the Database Engine.

  2. From the Standard bar, click New Query.

  3. Use the CREATE DATABASE statement with the FOR ATTACH clause.

    Copy and paste the following example into the query window and click Execute. This example attaches the files of the AdventureWorks2012 database and renames the database to MyAdventureWorks.

    CREATE DATABASE MyAdventureWorks   
        ON (FILENAME = 'C:\MySQLServer\AdventureWorks_Data.mdf'),   
        (FILENAME = 'C:\MySQLServer\AdventureWorks_Log.ldf')   
        FOR ATTACH;  


    Alternatively, you can use the sp_attach_db or sp_attach_single_file_db stored procedure. However, these procedures will be removed in a future version of Microsoft SQL Server. Avoid using this feature in new development work, and plan to modify applications that currently use this feature. We recommend that you use CREATE DATABASE ... FOR ATTACH instead.

Follow Up: After Upgrading a SQL Server Database

After you upgrade a database by using the attach method, the database becomes available immediately and is automatically upgraded. If the database has full-text indexes, the upgrade process either imports, resets, or rebuilds them, depending on the setting of the Full-Text Upgrade Option server property. If the upgrade option is set to Import or Rebuild, the full-text indexes will be unavailable during the upgrade. Depending the amount of data being indexed, importing can take several hours, and rebuilding can take up to ten times longer. Note also that when the upgrade option is set to Import, if a full-text catalog is not available, the associated full-text indexes are rebuilt.

After the upgrade, the database compatibility level remains at the compatibility level before the upgrade, unless the previous compatibility level is not supported on the new version. In this case, the upgraded database compatibility level is set to the lowest supported compatibility level.

For example, if you attach a database that was compatibility level 90 before attaching it to an instance of SQL Server 2019 (15.x), after the upgrade the compatibility level is set to 100, which is the lowest supported compatibility level in SQL Server 2019 (15.x). For more information, see ALTER DATABASE Compatibility Level (Transact-SQL).


If you are attaching a database from an instance running SQL Server 2014 (12.x) or below which had Change Data Capture (CDC) enabled, you will also need to execute the command below to upgrade the Change Data Capture (CDC) metadata.

USE <database name>
EXEC sys.sp_cdc_vupgrade  

See Also

Manage metadata when making a database available on another server
Detach a Database