Potresti provare (non testato) qualcosa come
select form_id,
max(case data_label when 'lastName' then data_value else null end) as lastname,
max(case data_label when 'firstName' then data_value else null end) as firstname,
max(case data_label when 'phone' then data_value else null end) as phone
from mytable
group by form_id
