Subsetting a data frame to the rows not appearing in another data frame

Question

I have a data frame A with observations

    Var1   Var2  Var3
     1       3    4
     2       5    6
     4       5    7
     4       5    8
     6       7    9         


        

Answer 1

Using sqldf is an option.

require(sqldf)

C <- sqldf('SELECT * FROM A EXCEPT SELECT * FROM B')