What's the R statement responding to SQL's 'in' statement?

Question

a case

df=data.frame(id=c(101,102,102,103,104,104,104),
         calmonth=c(\'01\',\'01\',\'01\',\'01\',\'01\',\'01\',\'02\'),
         product=c(\'         


        

Answer 1

If you prefer SQL syntax then use sqldf package:

library(sqldf)
sqldf("
      select * 
      from (
            select id,
                   calmonth,
                   group_concat(product, ' & ') product
            from df
            group by id, calmonth
           ) 
      where product='apple & htc' and
            calmonth='01'
      ")