SQL Server knowledge

What is the difference between the SQL server and the server group?

A server group is a logical concept, similar to a group of colleagues, friends, and family in a class or QQ. Generally, there are N students in the class. Students are equivalent to servers. It is just for convenience of organization. When there are too many servers, it is easy to find the servers in different groups.

What are the differences between the two authentication methods in SQL server?

Abstract: You need to modify something.
The system needs to verify your identity. After all, the database cannot be changed randomly.
Windows Authentication and SQL Server Authentication require you to present your identity documents.
Windows authentication is to show the identity of the windows account.
SQL Server authentication is a set of authentication mechanisms of SQL Server.
Different identities have different logon permissions.
For example, SA is the administrator identity, and the permissions are higher than ordinary identities.
SQL Server is the system administrator, windows is the user,
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