install.packages("sqldf")
library(sqldf)

mydata <- read.table("L:\\Daten\\01 Marco\\Programmierung\\R\\mydata.txt",
 header=TRUE,sep=",",row.names="id")

#sqldf("select * from df1 join df2 on df1.id=df2.id")

sqldf("select gender,count(*) as vol from mydata")

a=sqldf("select gender,count(*) as vol from mydata group by 1")

print(a)

print(sqldf("select gender,count(*) as vol from mydata group by 1"))