This is a heavily simplified version of an SQL problem I'm dealing with. Let's say I've got a table of all the cities in the world, like this:
country city
------------
Canada Montreal
Cuba Havanna
China Beijing
Canada Victoria
China Macau
I want to count how many cities each country has, so that I would end up with a table as such:
country city_count
------------------
Canada 50
Cuba 10
China 200
I know that I can get the distinct country values with SELECT distinct country FROM T1
and I suspect I need to construct a subquery for the city_count column. But my non-SQL brain is just telling me I need to loop through the results...
Thanks!
Assuming the only reason for a new row is a unique city
select country, count(country) AS City_Count
from table
group by country