Compute the number of distinct values in col2 for each distinct value in col1 in R

Question

I have a dataframe like this:

df <- data.frame(
          SchoolID=c(\"A\",\"A\",\"B\",\"B\",\"C\",\"D\"),
          Country=c(\"XX\",\"XX\",\"XX\",\"YY\"         


        

Answer 1

try this..

select School,count(Country)
from(
select distinct School,Country
from tbl_stacko) temp
group by School