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

Your SQL statement doesn't produce quite the result you show. It returns (selects) the IDs only not that table and the merged column? No?

SELECT id 
FROM   df 
WHERE  calmonth = '01' 
       AND product = "apple" 
       AND id IN (SELECT id 
                  FROM   df 
                  WHERE  product = "htc" 
                         AND calmonth = "01") 

in R that is roughly:

with(df, 
intersect(
id[calmonth=='01' & product=='apple'], 
id[product=="htc" & calmonth=="01"]))

[1] 102 104

Answer 2

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'
      ")