SQL Server fixed server roles

SQL Server has several fixed server roles that define the permissions and responsibilities of different users in a SQL Server instance. The following are the fixed server roles in SQL Server:

sysadmin: This is the highest-level role in SQL Server and has full administrative control over the entire instance. Members of this role can perform any action in the database, including creating, modifying, and deleting databases, as well as managing users, permissions, and server configurations.

serveradmin: Members of this role can perform a limited set of administrative tasks, such as configuring server-level settings and monitoring the health of the instance.

securityadmin: Members of this role can manage security-related tasks, such as creating and managing logins, users, and roles. They can also manage database permissions and encryptions.

processadmin: Members of this role can manage and monitor processes running on the instance. They can also kill processes if necessary.

Bulkadmin: Bulk insert operations means taking data out of files and putting them into database tables and that means interacting with elements outside of SQL Server itself. As a result, SQL Server has broken out the ability to carry out bulk insert operations to ensure you only allow it when you intend to. And that's what this role does. Typically, normal users do not need to be a member of this role. Only if they have to execute a BULK INSERT in their user context would they need such permission.

setupadmin: Members of this role can manage and maintain the SQL Server setup and installation process.

dbcreator: Members of this role can create and manage databases, but they cannot modify the instance-level configuration.

diskadmin: Members of this role can manage the physical storage of databases, including adding, modifying, and removing disk files.

These fixed server roles provide a hierarchical system of permissions in SQL Server, allowing administrators to control who has access to specific parts of the database and what they are allowed to do. It is recommended to assign users to roles that have the minimum level of permissions necessary to perform their job functions, to ensure the security and stability of the database.