It should be noted that the following although the easiest way to get a new database into an instance it should not be used in a production environment. In fact doing so may get you sacked. If experimenting though this method should be fine. If in doubt seek help as in a production environment you would want to look through all the code before attaching anything into an instance.
Go to SQL server management studio and on the Databases tree
Right click and select
Attach…..
Attach database window should appear which will allow you to use the Add… button to navigate to the
\Data\ subdirectory where all the sql server databases are held.
IMPORTANT – prior to loading a file in the database will have needed to have been DETACHED and you should always move anything mdf file that you are wanting to put into a database into the data subdirectory.
This ordinarily is done by going to database in question scrolling down to the database and right clicking on the database
Tasks > – Detach…
WARNING
If a database has not been detached properly it may NOT be possible to re-attach the database this is of course a security feature. So experimenting with simple moving files about will not work…
The listed code below does it at command line but the above works in SSMS
The default location for databases in SQL 08R2 Express is
C:\Program Files\Microsoft SQL Server\MSSQL10_50.SQLEXPRESS\MSSQL\DATA
The default location for database in SQL 2012 is
C:\Program Files\Microsoft SQL Server\MSSQL11.[InstanceName\MSSQL\DATA