When I run both queries individually, they run correctly. But when I try to combine both result sets into one table using the UNION operator, it doesn't run and I get the error message : "Syntax error: Top N option is not allowed in a query connected by set operators."
select
top 1
city,
count(*)
from unicorns
where city is not null and industry = 'Edtech'
group by city
order by 2 desc
union
select
top 1
city,
count(*)
from unicorns
where city is not null and industry = 'Internet software & services'
group by city
order by 2 desc
I would appreciate any help, Thanks.
Instead you can use window functions to achieve the same:
select
city,
count(*) ccount
from unicorns
where city is not null and industry = 'Edtech'
group by city
QUALIFY ROW_NUMBER() OVER (ORDER BY ccount DESC) = 1
union
select
city,
count(*) ccount
from unicorns
where city is not null and industry = 'Internet software & services'
group by city
QUALIFY ROW_NUMBER() OVER (ORDER BY ccount DESC) = 1
This way you aren't relying on ordering/top an interim result set (outside of partition ordering) and Teradata will be ok with it.