con <- dbConnect(RMySQL::MySQL(), host = "localhost",dbname="rbaseball"
             ,user = "root", password = "")
dbWriteTable(con, "mtcars", mtcars, overwrite = TRUE)
res <- dbSendQuery(con, "SELECT * FROM mtcars ORDER BY cyl")
dbApply(res, INDEX="cyl", FUN = function(x,grp) {quantile(x$mpg)})