Changing of Server Authentication Mode in SQL Server 2008 R2
During installation, SQL Server Database Engine is set to either Windows Authentication mode or SQL Server and Windows Authentication mode. This topic describes how to change the security mode after installation.
If Windows Authentication mode is selected during installation, the sa login is disabled and a password is assigned by setup. If you later change authentication mode to SQL Server and Windows Authentication mode, the sa login remains disabled. To use the sa login, use the ALTER LOGIN statement to enable the sa login and assign a new password.
Security Note:The sa account is a well-known SQL Server account and it is often targeted by malicious users. Do not enable the sa account unless your application requires it. It is very important that you use a strong password for the sa login.
To change security authentication mode
To restart SQL Server from SQL Server Management Studio
To enable the sa login by using Transact-SQL
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