The system security officer, the system administrator, or the database administrator creates a group using sp_addgroup group_name.
You can grant and revoke permissions at the group level. Group permissions are automatically passed to group members. Every database is created with a group named “public” to which all users automatically belong. Add a user to a group using sp_adduser and change a user’s group with sp_changegroup. See “Changing a user’s group membership”.
Groups are represented by an entry in the sysusers table. You cannot use the same name for creating a group and a user in the database (for example, you cannot have both a group and a user named “shirley”).
