Attach MDF File

If you have both .MDF and .LDF files and these files are shutdown properly, then you can attach the .MDF/.LDF files to SQL Server easily, as follows:

1. 1. Attach using SQL Server Management Studio:
      1. Start SQL Server Management Studio and connect to the server.
      2. Expand the instance, right-click Databases and click Attach.
      3. Follow the instructions in the Attach Databases dialog box to attach the .MDF/.LDF files to SQL Server.

      You can get more detailed info at :
      https://docs.microsoft.com/en-us/sql/relational-databases/databases/attach-a-database?view=sql-server-ver15

   2. Attach using SQL query:
      1. Start SQL Server Management Studio and connect to the server.
      2. Click New Query.
      3. Input the following command:

         sp_attach_db 'MyDB', 'C:MyDB_Data.mdf', 'C:MyDB_Log.ldf'
         
         or
         
         CREATE DATABASE MyDB
         ON (FILENAME = 'C:MyDB_Data.mdf'),
         (FILENAME = 'C:MyDB_Log.ldf')
         FOR ATTACH;
         

         Here, MyDB is the database name, C:MyDB_Data.mdf is the mdf file path, and C:MyDB_Log.ldf is the ldf file path.

         Microsoft recommends to use the second methods as the first method may retire in the new SQL Server versions.

      4. Click Execute to execute the query.

      You can also get more detailed info at :
      https://docs.microsoft.com/en-us/sql/relational-databases/databases/attach-a-database?view=sql-server-ver15

However, if your .MDF file and .LDF file is not shutdown properly. Or in other word, they are corrupt, then you need to use another method to attach them.