INSERT INTO grppriv (grppriv_grp_id, grppriv_priv_id)
SELECT (SELECT grp_id FROM grp WHERE grp_name = 'ROLE NAME HERE'),
usrpriv_priv_id
FROM usrpriv
WHERE usrpriv_username = 'NAME OF SOURCE USER';
replace the ROLE NAME HERE
with the name of the role you want as the target, and NAME OF SOURCE USER
with their proper values.