Assigning an sa Password
When you install Microsoft® SQL Server™, SQL Server Setup does not assign a password to the sa login. Assign a password to sa after a server is installed.
Assign an sa password if the server security is set for Mixed Mode. If the server is set for Windows Authentication Mode, an sa password is not necessary, because sa is a SQL Server login.
Important If you cannot provide the correct sa password, you must reinstall SQL Server.
The first time you log in to an instance of SQL Server, use sa as your login identification and no password. After you log in, change the sa password to prevent other users from using the sa permissions.
Note Before the sa password can be changed, the server must be registered to use SQL Server Enterprise Manager.
To assign the sa password on a newly installed server