sql - Get Roles which are still not assigned to member query -

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how query mysql database return roles still not assigned (like available him).

with table user_roles:

|user_id|role_id| |   1   |   1   | |   1   |   2   |  |   1   |   4   | |   1   |   7   |

how can query roles table return role name , id of roles not assigned. role_id: 3,5,8,...

try 

select * roles r not exists (    select 1    user_roles ur    ur.role_id = r.id    , ur.user_id = 1 )

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