# inner join merge(dt1, dt2, by = c("col1", "col2")) # left join merge(dt1, dt2, by = c("col1", "col2"), all.x = TRUE) # right join merge(dt1, dt2, by = c("col1", "col2"), all.y = TRUE)
# inner join merge(dt1, dt2, by = c("col1", "col2")) # left join merge(dt1, dt2, by = c("col1", "col2"), all.x = TRUE) # right join merge(dt1, dt2, by = c("col1", "col2"), all.y = TRUE)