role_contain( ‘role_1’, ‘role_2’ )
Returns 1 if role_2 contains role_1; otherwise returns 0.
Example
create role Role_inner
create role Role_outer
grant role Role_outer to Role_inner
select Role_contain( 'Role_inner', 'Role_outer' )
select Role_contain( 'Role_outer', 'Role_inner' )
drop role Role_outer
drop role Role_inner