Microsoft SQL Server Database permissions Changing role membership
Example
-- SQL 2005+
exec sp_addrolemember @rolename = 'myRole', @membername = 'aUser';
exec sp_droprolemember @rolename = 'myRole', @membername = 'aUser';
-- SQL 2008+
ALTER ROLE [myRole] ADD MEMBER [aUser];
ALTER ROLE [myRole] DROP MEMBER [aUser];
Note: role members can be any database-level principal. That is, you can add a role as a member in another role. Also, adding/dropping role members is idempotent. That is, attempting to add/drop will result in their presence/absence (respectively) in the role regardless of the current state of their role membership.
