Server roles are maintained by the database administrator (DBA) and apply to the entire server, not an individual database file. The public role sets the basic default permissions for all users. Every user that’s added to SQL Server is automatically assigned to the public role—you don’t need to do anything. Database roles are applied to an individual database.
Predefined database roles:
You may need to create your own, but you have access to several predefined database roles:
db_owner: Members have full access.
db_accessadmin: Members can manage Windows groups and SQL Server logins.
db_datareader: Members can read all data.
db_datawriter: Members can add, delete, or modify data in the tables.
db_ddladmin: Members can run dynamic-link library (DLL) statements.
db_securityadmin: Members can modify role membership and manage permissions.
db_bckupoperator: Members can back up the database.
db_denydatareader: Members can’t view data within the database.
db_denydatawriter: Members can’t change or delete data in tables or views.
The fixed server roles are applied serverwide, and there are several predefined server roles:
SysAdmin: Any member can perform any action on the server.
ServerAdmin: Any member can set configuration options on the server.
SetupAdmin: Any member can manage linked servers and SQL Server startup options and tasks.
Security Admin: Any member can manage server security.
ProcessAdmin: Any member can kill processes running on SQL Server.
DbCreator: Any member can create, alter, drop, and restore databases.
DiskAdmin: Any member can manage SQL Server disk files.
BulkAdmin: Any member can run the bulk insert command.