आप union all
. का उपयोग कर सकते हैं अपने डेटासेट और फिर एग्रीगेशन को अनपिवट करने के लिए:
select disease, count(*) total
from (
select disease from mytable
union all select additional_disease1 from mytable
union all select additional_disease2 from mytable
union all select additional_disease3 from mytable
union all select additional_disease4 from mytable
) t
group by disease
order by total desc, disease