Description of database roles in sqlserver

Role
When several users need to perform similar actions in a specific database (there is no corresponding Windows user group), they can add a role to the database ). The database role specifies a group of database users who can access the same database object.

Database roles can be divided into the following types:

Windows user group or user account

SQL Server Logon

Other roles

The security architecture of SQL Server includes several roles with specific implicit permissions. In addition to the roles created by the database owner, there are two types of predefined roles. The roles that can be created can be divided into the following categories:

Fixed Server

Fixed Database

User-Defined